diff --git a/src/Umbraco.Core/Composing/DefaultUmbracoAssemblyProvider.cs b/src/Umbraco.Core/Composing/DefaultUmbracoAssemblyProvider.cs
new file mode 100644
index 0000000000..61d7cff240
--- /dev/null
+++ b/src/Umbraco.Core/Composing/DefaultUmbracoAssemblyProvider.cs
@@ -0,0 +1,47 @@
+using System;
+using System.Collections.Generic;
+using System.Reflection;
+
+namespace Umbraco.Core.Composing
+{
+    /// <summary>
+    /// Returns a list of scannable assemblies based on an entry point assembly and it's references
+    /// </summary>
+    /// <remarks>
+    /// This will recursively search through the entry point's assemblies and Umbraco's core assemblies and their references
+    /// to create a list of scannable assemblies based on whether they themselves or their transitive dependencies reference Umbraco core assemblies.
+    /// </remarks>
+    public class DefaultUmbracoAssemblyProvider : IAssemblyProvider
+    {
+        private readonly Assembly _entryPointAssembly;
+        private static readonly string[] UmbracoCoreAssemblyNames = new[]
+            {
+                "Umbraco.Core",
+                "Umbraco.Web",
+                "Umbraco.Infrastructure",
+                "Umbraco.PublishedCache.NuCache",
+                "Umbraco.ModelsBuilder.Embedded",
+                "Umbraco.Examine.Lucene",
+            };
+
+        public DefaultUmbracoAssemblyProvider(Assembly entryPointAssembly)
+        {
+            _entryPointAssembly = entryPointAssembly ?? throw new ArgumentNullException(nameof(entryPointAssembly));
+        }
+
+        // TODO: It would be worth investigating a netcore3 version of this which would use
+        // var allAssemblies = System.Runtime.Loader.AssemblyLoadContext.All.SelectMany(x => x.Assemblies);
+        // that will still only resolve Assemblies that are already loaded but it would also make it possible to
+        // query dynamically generated assemblies once they are added. It would also provide the ability to probe
+        // assembly locations that are not in the same place as the entry point assemblies.
+
+        public IEnumerable<Assembly> Assemblies
+        {
+            get
+            {
+                var finder = new FindAssembliesWithReferencesTo(new[] { _entryPointAssembly }, UmbracoCoreAssemblyNames, true);
+                return finder.Find();
+            }
+        }
+    }
+}
diff --git a/src/Umbraco.Core/Composing/FindAssembliesWithReferencesTo.cs b/src/Umbraco.Core/Composing/FindAssembliesWithReferencesTo.cs
new file mode 100644
index 0000000000..91225ff973
--- /dev/null
+++ b/src/Umbraco.Core/Composing/FindAssembliesWithReferencesTo.cs
@@ -0,0 +1,55 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Reflection;
+
+namespace Umbraco.Core.Composing
+{
+    /// <summary>
+    /// Finds Assemblies from the entry point assemblies, it's dependencies and it's transitive dependencies that reference that targetAssemblyNames
+    /// </summary>
+    /// <remarkes>
+    /// borrowed and modified from here https://github.com/dotnet/aspnetcore-tooling/blob/master/src/Razor/src/Microsoft.NET.Sdk.Razor/FindAssembliesWithReferencesTo.cs
+    /// </remarkes>
+    internal class FindAssembliesWithReferencesTo
+    {
+        private readonly Assembly[] _referenceAssemblies;
+        private readonly string[] _targetAssemblies;
+        private readonly bool _includeTargets;
+
+        /// <summary>
+        /// Constructor
+        /// </summary>
+        /// <param name="referenceAssemblies">Entry point assemblies</param>
+        /// <param name="targetAssemblyNames">Used to check if the entry point or it's transitive assemblies reference these assembly names</param>
+        /// <param name="includeTargets">If true will also use the target assembly names as entry point assemblies</param>
+        public FindAssembliesWithReferencesTo(Assembly[] referenceAssemblies, string[] targetAssemblyNames, bool includeTargets)
+        {
+            _referenceAssemblies = referenceAssemblies;
+            _targetAssemblies = targetAssemblyNames;
+            _includeTargets = includeTargets;
+        }
+
+        public IEnumerable<Assembly> Find()
+        {
+            var referenceItems = new List<Assembly>();
+            foreach (var assembly in _referenceAssemblies)
+            {
+                referenceItems.Add(assembly);
+            }
+
+            if (_includeTargets)
+            {
+                foreach(var target in _targetAssemblies)
+                {
+                    referenceItems.Add(Assembly.Load(target));
+                }
+            }
+
+            var provider = new ReferenceResolver(_targetAssemblies, referenceItems);
+            var assemblyNames = provider.ResolveAssemblies();
+            return assemblyNames.ToList();
+        }
+
+    }
+}
diff --git a/src/Umbraco.Core/Composing/IAssemblyProvider.cs b/src/Umbraco.Core/Composing/IAssemblyProvider.cs
new file mode 100644
index 0000000000..bde97a9556
--- /dev/null
+++ b/src/Umbraco.Core/Composing/IAssemblyProvider.cs
@@ -0,0 +1,13 @@
+using System.Collections.Generic;
+using System.Reflection;
+
+namespace Umbraco.Core.Composing
+{
+    /// <summary>
+    /// Provides a list of assemblies that can be scanned
+    /// </summary>
+    public interface IAssemblyProvider
+    {
+        IEnumerable<Assembly> Assemblies { get; }
+    }
+}
diff --git a/src/Umbraco.Core/Composing/ReferenceResolver.cs b/src/Umbraco.Core/Composing/ReferenceResolver.cs
new file mode 100644
index 0000000000..65dba8bf23
--- /dev/null
+++ b/src/Umbraco.Core/Composing/ReferenceResolver.cs
@@ -0,0 +1,173 @@
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.IO;
+using System.Linq;
+using System.Reflection;
+
+namespace Umbraco.Core.Composing
+{
+    /// <summary>
+    /// Resolves assemblies that reference one of the specified "targetAssemblies" either directly or transitively.
+    /// </summary>
+    /// <remarks>
+    /// Borrowed and modified from https://github.com/dotnet/aspnetcore-tooling/blob/master/src/Razor/src/Microsoft.NET.Sdk.Razor/ReferenceResolver.cs
+    /// </remarks>
+    internal class ReferenceResolver
+    {
+        private readonly HashSet<string> _umbracoAssemblies;
+        private readonly IReadOnlyList<Assembly> _assemblies;
+        private readonly Dictionary<Assembly, Classification> _classifications;
+        private readonly List<Assembly> _lookup = new List<Assembly>();
+
+        public ReferenceResolver(IReadOnlyList<string> targetAssemblies, IReadOnlyList<Assembly> entryPointAssemblies)
+        {
+            _umbracoAssemblies = new HashSet<string>(targetAssemblies, StringComparer.Ordinal);
+            _assemblies = entryPointAssemblies;
+            _classifications = new Dictionary<Assembly, Classification>();
+
+            foreach (var item in entryPointAssemblies)
+            {
+                _lookup.Add(item);
+            }
+        }
+
+        /// <summary>
+        /// Returns a list of assemblies that directly reference or transitively reference the targetAssemblies
+        /// </summary>
+        /// <returns></returns>
+        /// <remarks>
+        /// This includes all assemblies in the same location as the entry point assemblies
+        /// </remarks>
+        public IEnumerable<Assembly> ResolveAssemblies()
+        {
+            var applicationParts = new List<Assembly>();
+
+            var assemblies = new HashSet<Assembly>(_assemblies);
+
+            // Get the unique directories of the assemblies
+            var assemblyLocations = GetAssemblyFolders(assemblies).ToList();
+
+            // Load in each assembly in the directory of the entry assembly to be included in the search
+            // for Umbraco dependencies/transitive dependencies
+            foreach(var dir in assemblyLocations)
+            {   
+                foreach(var dll in Directory.EnumerateFiles(dir, "*.dll"))
+                {
+                    var assemblyName = AssemblyName.GetAssemblyName(dll);
+
+                    // don't include if this is excluded
+                    if (TypeFinder.KnownAssemblyExclusionFilter.Any(f => assemblyName.FullName.StartsWith(f, StringComparison.InvariantCultureIgnoreCase)))
+                        continue;
+
+                    // don't include this item if it's Umbraco
+                    // TODO: We should maybe pass an explicit list of these names in?
+                    if (assemblyName.FullName.StartsWith("Umbraco."))
+                        continue;
+
+                    var assembly = Assembly.Load(assemblyName);
+                    assemblies.Add(assembly);
+                }
+            }
+
+            foreach (var item in assemblies)
+            {
+                var classification = Resolve(item);
+                if (classification == Classification.ReferencesUmbraco || classification == Classification.IsUmbraco)
+                {
+                    applicationParts.Add(item);
+                }
+            }
+
+            return applicationParts;
+        }
+
+
+        private IEnumerable<string> GetAssemblyFolders(IEnumerable<Assembly> assemblies)
+        {
+            return assemblies.Select(x => Path.GetDirectoryName(GetAssemblyLocation(x)).ToLowerInvariant()).Distinct();
+        }
+
+        // borrowed from https://github.com/dotnet/aspnetcore/blob/master/src/Mvc/Mvc.Core/src/ApplicationParts/RelatedAssemblyAttribute.cs
+        private string GetAssemblyLocation(Assembly assembly)
+        {
+            if (Uri.TryCreate(assembly.CodeBase, UriKind.Absolute, out var result) &&
+                result.IsFile && string.IsNullOrWhiteSpace(result.Fragment))
+            {
+                return result.LocalPath;
+            }
+
+            return assembly.Location;
+        }
+
+        private Classification Resolve(Assembly assembly)
+        {
+            if (_classifications.TryGetValue(assembly, out var classification))
+            {
+                return classification;
+            }
+
+            // Initialize the dictionary with a value to short-circuit recursive references.
+            classification = Classification.Unknown;
+            _classifications[assembly] = classification;
+            
+            if (TypeFinder.KnownAssemblyExclusionFilter.Any(f => assembly.FullName.StartsWith(f, StringComparison.InvariantCultureIgnoreCase)))
+            {
+                // if its part of the filter it doesn't reference umbraco
+                classification = Classification.DoesNotReferenceUmbraco;
+            }                
+            else if (_umbracoAssemblies.Contains(assembly.GetName().Name))
+            {
+                classification = Classification.IsUmbraco;
+            }
+            else
+            {
+                classification = Classification.DoesNotReferenceUmbraco;
+                foreach (var reference in GetReferences(assembly))
+                {
+                    // recurse
+                    var referenceClassification = Resolve(reference);
+
+                    if (referenceClassification == Classification.IsUmbraco || referenceClassification == Classification.ReferencesUmbraco)
+                    {
+                        classification = Classification.ReferencesUmbraco;
+                        break;
+                    }
+                }
+            }
+
+            Debug.Assert(classification != Classification.Unknown);
+            _classifications[assembly] = classification;
+            return classification;
+        }
+
+        protected virtual IEnumerable<Assembly> GetReferences(Assembly assembly)
+        {            
+            foreach (var referenceName in assembly.GetReferencedAssemblies())
+            {
+                // don't include if this is excluded
+                if (TypeFinder.KnownAssemblyExclusionFilter.Any(f => referenceName.FullName.StartsWith(f, StringComparison.InvariantCultureIgnoreCase)))
+                    continue;
+
+                var reference = Assembly.Load(referenceName);
+
+                if (!_lookup.Contains(reference))
+                {
+                    // A dependency references an item that isn't referenced by this project.
+                    // We'll add this reference so that we can calculate the classification.
+
+                    _lookup.Add(reference);                    
+                }
+                yield return reference;
+            }
+        }
+
+        protected enum Classification
+        {
+            Unknown,
+            DoesNotReferenceUmbraco,
+            ReferencesUmbraco,
+            IsUmbraco,
+        }
+    }
+}
diff --git a/src/Umbraco.Core/Composing/TypeFinder.cs b/src/Umbraco.Core/Composing/TypeFinder.cs
index 9d88153b0a..79fddad1ca 100644
--- a/src/Umbraco.Core/Composing/TypeFinder.cs
+++ b/src/Umbraco.Core/Composing/TypeFinder.cs
@@ -1,106 +1,35 @@
 using System;
 using System.Collections.Concurrent;
 using System.Collections.Generic;
-using System.Configuration;
-using System.IO;
 using System.Linq;
 using System.Reflection;
 using System.Security;
 using System.Text;
 using Umbraco.Core.Configuration.UmbracoSettings;
-using Umbraco.Core.Exceptions;
-using Umbraco.Core.IO;
 using Umbraco.Core.Logging;
 
 namespace Umbraco.Core.Composing
 {
+
     /// <inheritdoc cref="ITypeFinder"/>
     public class TypeFinder : ITypeFinder
     {
         private readonly ILogger _logger;
-
-        public TypeFinder(ILogger logger, ITypeFinderConfig typeFinderConfig = null)
-        {
-            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
-            _assembliesAcceptingLoadExceptions = typeFinderConfig?.AssembliesAcceptingLoadExceptions.Where(x => !x.IsNullOrWhiteSpace()).ToArray() ?? Array.Empty<string>();
-            _allAssemblies = new Lazy<HashSet<Assembly>>(() =>
-            {
-                HashSet<Assembly> assemblies = null;
-                try
-                {
-                    //NOTE: we cannot use AppDomain.CurrentDomain.GetAssemblies() because this only returns assemblies that have
-                    // already been loaded in to the app domain, instead we will look directly into the bin folder and load each one.
-                    var binFolder = GetRootDirectorySafe();
-                    var binAssemblyFiles = Directory.GetFiles(binFolder, "*.dll", SearchOption.TopDirectoryOnly).ToList();
-                    //var binFolder = Assembly.GetExecutingAssembly().GetAssemblyFile().Directory;
-                    //var binAssemblyFiles = Directory.GetFiles(binFolder.FullName, "*.dll", SearchOption.TopDirectoryOnly).ToList();
-                    assemblies = new HashSet<Assembly>();
-                    foreach (var a in binAssemblyFiles)
-                    {
-                        try
-                        {
-                            var assName = AssemblyName.GetAssemblyName(a);
-                            var ass = Assembly.Load(assName);
-                            assemblies.Add(ass);
-                        }
-                        catch (Exception e)
-                        {
-                            if (e is SecurityException || e is BadImageFormatException)
-                            {
-                                //swallow these exceptions
-                            }
-                            else
-                            {
-                                throw;
-                            }
-                        }
-                    }
-
-                    //Since we are only loading in the /bin assemblies above, we will also load in anything that's already loaded (which will include gac items)
-                    foreach (var a in AppDomain.CurrentDomain.GetAssemblies())
-                    {
-                        assemblies.Add(a);
-                    }
-                }
-                catch (InvalidOperationException e)
-                {
-                    if (e.InnerException is SecurityException == false)
-                        throw;
-                }
-
-                return assemblies;
-            });
-        }
-
-        //Lazy access to the all assemblies list
-        private readonly Lazy<HashSet<Assembly>> _allAssemblies;
+        private readonly IAssemblyProvider _assemblyProvider;
         private volatile HashSet<Assembly> _localFilteredAssemblyCache;
         private readonly object _localFilteredAssemblyCacheLocker = new object();
         private readonly List<string> _notifiedLoadExceptionAssemblies = new List<string>();
-        private static readonly ConcurrentDictionary<string, Type> TypeNamesCache= new ConcurrentDictionary<string, Type>();
-        private string _rootDir = "";
+        private static readonly ConcurrentDictionary<string, Type> TypeNamesCache = new ConcurrentDictionary<string, Type>();
         private readonly string[] _assembliesAcceptingLoadExceptions;
 
-        // FIXME - this is only an interim change, once the IIOHelper stuff is merged we should use IIOHelper here
-        private string GetRootDirectorySafe()
+        // used for benchmark tests
+        internal bool QueryWithReferencingAssemblies = true;
+
+        public TypeFinder(ILogger logger, IAssemblyProvider assemblyProvider, ITypeFinderConfig typeFinderConfig = null)
         {
-            if (string.IsNullOrEmpty(_rootDir) == false)
-            {
-                return _rootDir;
-            }
-
-            var codeBase = Assembly.GetExecutingAssembly().CodeBase;
-            var uri = new Uri(codeBase);
-            var path = uri.LocalPath;
-            var baseDirectory = Path.GetDirectoryName(path);
-            if (string.IsNullOrEmpty(baseDirectory))
-                throw new PanicException("No root directory could be resolved.");
-
-            _rootDir = baseDirectory.Contains("bin")
-                ? baseDirectory.Substring(0, baseDirectory.LastIndexOf("bin", StringComparison.OrdinalIgnoreCase) - 1)
-                : baseDirectory;
-
-            return _rootDir;
+            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+            _assemblyProvider = assemblyProvider;
+            _assembliesAcceptingLoadExceptions = typeFinderConfig?.AssembliesAcceptingLoadExceptions.Where(x => !x.IsNullOrWhiteSpace()).ToArray() ?? Array.Empty<string>();           
         }
 
         private bool AcceptsLoadExceptions(Assembly a)
@@ -119,22 +48,8 @@ namespace Umbraco.Core.Composing
             });
         }
 
-        /// <summary>
-        /// lazily load a reference to all assemblies and only local assemblies.
-        /// This is a modified version of: http://www.dominicpettifer.co.uk/Blog/44/how-to-get-a-reference-to-all-assemblies-in-the--bin-folder
-        /// </summary>
-        /// <remarks>
-        /// We do this because we cannot use AppDomain.Current.GetAssemblies() as this will return only assemblies that have been
-        /// loaded in the CLR, not all assemblies.
-        /// See these threads:
-        /// http://issues.umbraco.org/issue/U5-198
-        /// http://stackoverflow.com/questions/3552223/asp-net-appdomain-currentdomain-getassemblies-assemblies-missing-after-app
-        /// http://stackoverflow.com/questions/2477787/difference-between-appdomain-getassemblies-and-buildmanager-getreferencedassembl
-        /// </remarks>
-        private IEnumerable<Assembly> GetAllAssemblies()
-        {
-            return _allAssemblies.Value;
-        }
+
+        private IEnumerable<Assembly> GetAllAssemblies() => _assemblyProvider.Assemblies;
 
         /// <inheritdoc />
         public IEnumerable<Assembly> AssembliesToScan
@@ -181,7 +96,10 @@ namespace Umbraco.Core.Composing
         /// NOTE the comma vs period... comma delimits the name in an Assembly FullName property so if it ends with comma then its an exact name match
         /// NOTE this means that "foo." will NOT exclude "foo.dll" but only "foo.*.dll"
         /// </remarks>
-        private static readonly string[] KnownAssemblyExclusionFilter = {
+        internal static readonly string[] KnownAssemblyExclusionFilter = {
+            "mscorlib,",
+            "netstandard,",
+            "System,",
             "Antlr3.",
             "AutoMapper,",
             "AutoMapper.",
@@ -228,7 +146,14 @@ namespace Umbraco.Core.Composing
             "WebDriver,",
             "itextsharp,",
             "mscorlib,",
-            "nunit.framework,",
+            "NUnit,",
+            "NUnit.",
+            "NUnit3.",
+            "Selenium.",
+            "ImageProcessor",
+            "MiniProfiler.",
+            "Owin,",
+            "SQLite",
         };
 
         /// <summary>
@@ -290,6 +215,11 @@ namespace Umbraco.Core.Composing
         /// <returns></returns>
         public virtual Type GetTypeByName(string name)
         {
+
+            //NOTE: This will not find types in dynamic assemblies unless those assemblies are already loaded
+            //into the appdomain.
+
+
             // This is exactly what the BuildManager does, if the type is an assembly qualified type
             // name it will find it.
             if (TypeNameContainsAssembly(name))
@@ -340,18 +270,24 @@ namespace Umbraco.Core.Composing
             var stack = new Stack<Assembly>();
             stack.Push(attributeType.Assembly);
 
+            if (!QueryWithReferencingAssemblies)
+            {
+                foreach (var a in candidateAssemblies)
+                    stack.Push(a);
+            }
+
             while (stack.Count > 0)
             {
                 var assembly = stack.Pop();
 
-                Type[] assemblyTypes = null;
+                IReadOnlyList<Type> assemblyTypes = null;
                 if (assembly != attributeType.Assembly || attributeAssemblyIsCandidate)
                 {
                     // get all assembly types that can be assigned to baseType
                     try
                     {
                         assemblyTypes = GetTypesWithFormattedException(assembly)
-                            .ToArray(); // in try block
+                            .ToList(); // in try block
                     }
                     catch (TypeLoadException ex)
                     {
@@ -371,10 +307,13 @@ namespace Umbraco.Core.Composing
                 if (assembly != attributeType.Assembly && assemblyTypes.Where(attributeType.IsAssignableFrom).Any() == false)
                     continue;
 
-                foreach (var referencing in TypeHelper.GetReferencingAssemblies(assembly, candidateAssemblies))
+                if (QueryWithReferencingAssemblies)
                 {
-                    candidateAssemblies.Remove(referencing);
-                    stack.Push(referencing);
+                    foreach (var referencing in TypeHelper.GetReferencingAssemblies(assembly, candidateAssemblies))
+                    {
+                        candidateAssemblies.Remove(referencing);
+                        stack.Push(referencing);
+                    }
                 }
             }
 
@@ -405,19 +344,25 @@ namespace Umbraco.Core.Composing
             var stack = new Stack<Assembly>();
             stack.Push(baseType.Assembly);
 
+            if (!QueryWithReferencingAssemblies)
+            {
+                foreach (var a in candidateAssemblies)
+                    stack.Push(a);
+            }
+
             while (stack.Count > 0)
             {
                 var assembly = stack.Pop();
 
                 // get all assembly types that can be assigned to baseType
-                Type[] assemblyTypes = null;
+                IReadOnlyList<Type> assemblyTypes = null;
                 if (assembly != baseType.Assembly || baseTypeAssemblyIsCandidate)
                 {
                     try
                     {
                         assemblyTypes = GetTypesWithFormattedException(assembly)
                             .Where(baseType.IsAssignableFrom)
-                            .ToArray(); // in try block
+                            .ToList(); // in try block
                     }
                     catch (TypeLoadException ex)
                     {
@@ -437,10 +382,13 @@ namespace Umbraco.Core.Composing
                 if (assembly != baseType.Assembly && assemblyTypes.All(x => x.IsSealed))
                     continue;
 
-                foreach (var referencing in TypeHelper.GetReferencingAssemblies(assembly, candidateAssemblies))
+                if (QueryWithReferencingAssemblies)
                 {
-                    candidateAssemblies.Remove(referencing);
-                    stack.Push(referencing);
+                    foreach (var referencing in TypeHelper.GetReferencingAssemblies(assembly, candidateAssemblies))
+                    {
+                        candidateAssemblies.Remove(referencing);
+                        stack.Push(referencing);
+                    }
                 }
             }
 
@@ -522,6 +470,5 @@ namespace Umbraco.Core.Composing
 
         #endregion
 
-
     }
 }
diff --git a/src/Umbraco.Core/Composing/TypeFinderConfig.cs b/src/Umbraco.Core/Composing/TypeFinderConfig.cs
new file mode 100644
index 0000000000..3dc672b27c
--- /dev/null
+++ b/src/Umbraco.Core/Composing/TypeFinderConfig.cs
@@ -0,0 +1,36 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using Umbraco.Core.Configuration;
+using Umbraco.Core.Configuration.UmbracoSettings;
+
+namespace Umbraco.Core.Composing
+{
+    /// <summary>
+    /// TypeFinder config via appSettings
+    /// </summary>
+    internal class TypeFinderConfig : ITypeFinderConfig
+    {
+        private readonly ITypeFinderSettings _settings;
+        private IEnumerable<string> _assembliesAcceptingLoadExceptions;
+
+        public TypeFinderConfig(ITypeFinderSettings settings)
+        {
+            _settings = settings;
+        }
+
+        public IEnumerable<string> AssembliesAcceptingLoadExceptions
+        {
+            get
+            {
+                if (_assembliesAcceptingLoadExceptions != null)
+                    return _assembliesAcceptingLoadExceptions;
+
+                var s = _settings.AssembliesAcceptingLoadExceptions;
+                return _assembliesAcceptingLoadExceptions = string.IsNullOrWhiteSpace(s)
+                    ? Array.Empty<string>()
+                    : s.Split(',').Select(x => x.Trim()).ToArray();
+            }
+        }
+    }
+}
diff --git a/src/Umbraco.Core/Composing/TypeHelper.cs b/src/Umbraco.Core/Composing/TypeHelper.cs
index 28eab6a5ec..1987a4059c 100644
--- a/src/Umbraco.Core/Composing/TypeHelper.cs
+++ b/src/Umbraco.Core/Composing/TypeHelper.cs
@@ -82,9 +82,9 @@ namespace Umbraco.Core.Composing
         /// If the assembly of the assignTypeFrom Type is in the App_Code assembly, then we return nothing since things cannot
         /// reference that assembly, same with the global.asax assembly.
         /// </remarks>
-        public static Assembly[] GetReferencingAssemblies(Assembly assembly, IEnumerable<Assembly> assemblies)
+        public static IReadOnlyList<Assembly> GetReferencingAssemblies(Assembly assembly, IEnumerable<Assembly> assemblies)
         {
-            if (assembly.IsAppCodeAssembly() || assembly.IsGlobalAsaxAssembly())
+            if (assembly.IsDynamic || assembly.IsAppCodeAssembly() || assembly.IsGlobalAsaxAssembly())
                 return EmptyAssemblies;
 
 
@@ -92,7 +92,7 @@ namespace Umbraco.Core.Composing
             // should only be scanning those assemblies because any other assembly will definitely not
             // contain sub type's of the one we're currently looking for
             var name = assembly.GetName().Name;
-            return assemblies.Where(x => x == assembly || HasReference(x, name)).ToArray();
+            return assemblies.Where(x => x == assembly || HasReference(x, name)).ToList();
         }
 
         /// <summary>
diff --git a/src/Umbraco.Core/Composing/TypeLoader.cs b/src/Umbraco.Core/Composing/TypeLoader.cs
index 76d00c472d..4d8b5c984c 100644
--- a/src/Umbraco.Core/Composing/TypeLoader.cs
+++ b/src/Umbraco.Core/Composing/TypeLoader.cs
@@ -516,29 +516,29 @@ namespace Umbraco.Core.Composing
 
         #region Get Assembly Attributes
 
-        /// <summary>
-        /// Gets the assembly attributes of the specified type <typeparamref name="T" />.
-        /// </summary>
-        /// <typeparam name="T">The attribute type.</typeparam>
-        /// <returns>
-        /// The assembly attributes of the specified type <typeparamref name="T" />.
-        /// </returns>
-        public IEnumerable<T> GetAssemblyAttributes<T>()
-            where T : Attribute
-        {
-            return AssembliesToScan.SelectMany(a => a.GetCustomAttributes<T>()).ToList();
-        }
+        ///// <summary>
+        ///// Gets the assembly attributes of the specified type <typeparamref name="T" />.
+        ///// </summary>
+        ///// <typeparam name="T">The attribute type.</typeparam>
+        ///// <returns>
+        ///// The assembly attributes of the specified type <typeparamref name="T" />.
+        ///// </returns>
+        //public IEnumerable<T> GetAssemblyAttributes<T>()
+        //    where T : Attribute
+        //{
+        //    return AssembliesToScan.SelectMany(a => a.GetCustomAttributes<T>()).ToList();
+        //}
 
-        /// <summary>
-        /// Gets all the assembly attributes.
-        /// </summary>
-        /// <returns>
-        /// All assembly attributes.
-        /// </returns>
-        public IEnumerable<Attribute> GetAssemblyAttributes()
-        {
-            return AssembliesToScan.SelectMany(a => a.GetCustomAttributes()).ToList();
-        }
+        ///// <summary>
+        ///// Gets all the assembly attributes.
+        ///// </summary>
+        ///// <returns>
+        ///// All assembly attributes.
+        ///// </returns>
+        //public IEnumerable<Attribute> GetAssemblyAttributes()
+        //{
+        //    return AssembliesToScan.SelectMany(a => a.GetCustomAttributes()).ToList();
+        //}
 
         /// <summary>
         /// Gets the assembly attributes of the specified <paramref name="attributeTypes" />.
diff --git a/src/Umbraco.Infrastructure/Runtime/CoreRuntime.cs b/src/Umbraco.Infrastructure/Runtime/CoreRuntime.cs
index 38731ce21c..7b1aff1a4b 100644
--- a/src/Umbraco.Infrastructure/Runtime/CoreRuntime.cs
+++ b/src/Umbraco.Infrastructure/Runtime/CoreRuntime.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.IO;
+using System.Reflection;
 using Umbraco.Core.Cache;
 using Umbraco.Core.Composing;
 using Umbraco.Core.Configuration;
@@ -369,7 +370,21 @@ namespace Umbraco.Core.Runtime
         /// </summary>
         /// <returns></returns>
         protected virtual ITypeFinder GetTypeFinder()
-            => new TypeFinder(Logger);
+            // TODO: Currently we are not passing in any TypeFinderConfig (with ITypeFinderSettings) which we should do, however
+            // this is not critical right now and would require loading in some config before boot time so just leaving this as-is for now.
+            => new TypeFinder(Logger, new DefaultUmbracoAssemblyProvider(
+                // GetEntryAssembly was actually an exposed API by request of the aspnetcore team which works in aspnet core because a website
+                // in that case is essentially an exe. However in netframework there is no entry assembly, things don't really work that way since
+                // the process that is running the site is iisexpress, so this returns null. The best we can do is fallback to GetExecutingAssembly()
+                // which will just return Umbraco.Infrastructure (currently with netframework) and for our purposes that is OK.
+                // If you are curious... There is really no way to get the entry assembly in netframework without the hosting website having it's own
+                // code compiled for the global.asax which is the entry point. Because the default global.asax for umbraco websites is just a file inheriting
+                // from Umbraco.Web.UmbracoApplication, the global.asax file gets dynamically compiled into a DLL in the dynamic folder (we can get an instance
+                // of that, but this doesn't really help us) but the actually entry execution is still Umbraco.Web. So that is the 'highest' level entry point
+                // assembly we can get and we can only get that if we put this code into the WebRuntime since the executing assembly is the 'current' one.
+                // For this purpose, it doesn't matter if it's Umbraco.Web or Umbraco.Infrastructure since all assemblies are in that same path and we are
+                // getting rid of netframework.
+                Assembly.GetEntryAssembly() ?? Assembly.GetExecutingAssembly()));
 
 
         /// <summary>
diff --git a/src/Umbraco.Tests.Benchmarks/TypeFinderBenchmarks.cs b/src/Umbraco.Tests.Benchmarks/TypeFinderBenchmarks.cs
new file mode 100644
index 0000000000..7b4322bfac
--- /dev/null
+++ b/src/Umbraco.Tests.Benchmarks/TypeFinderBenchmarks.cs
@@ -0,0 +1,30 @@
+using BenchmarkDotNet.Attributes;
+using System;
+using System.Linq;
+using Umbraco.Core.Composing;
+using Umbraco.Core.Logging;
+using Umbraco.Tests.Benchmarks.Config;
+
+namespace Umbraco.Tests.Benchmarks
+{
+    [MediumRunJob]
+    [MemoryDiagnoser]
+    public class TypeFinderBenchmarks
+    {
+
+        [Benchmark(Baseline = true)]
+        public void WithGetReferencingAssembliesCheck()
+        {
+            var typeFinder1 = new TypeFinder(new NullLogger(), new DefaultUmbracoAssemblyProvider(GetType().Assembly));
+            var found = typeFinder1.FindClassesOfType<IDiscoverable>().Count();
+        }
+
+        [Benchmark]
+        public void WithoutGetReferencingAssembliesCheck()
+        {
+            var typeFinder2 = new TypeFinder(new NullLogger(), new DefaultUmbracoAssemblyProvider(GetType().Assembly));
+            typeFinder2.QueryWithReferencingAssemblies = false;
+            var found = typeFinder2.FindClassesOfType<IDiscoverable>().Count();
+        }
+    }
+}
diff --git a/src/Umbraco.Tests.Benchmarks/Umbraco.Tests.Benchmarks.csproj b/src/Umbraco.Tests.Benchmarks/Umbraco.Tests.Benchmarks.csproj
index 7566d8ab85..84ec535b9d 100644
--- a/src/Umbraco.Tests.Benchmarks/Umbraco.Tests.Benchmarks.csproj
+++ b/src/Umbraco.Tests.Benchmarks/Umbraco.Tests.Benchmarks.csproj
@@ -61,6 +61,7 @@
     <Compile Include="SqlTemplatesBenchmark.cs" />
     <Compile Include="StringReplaceManyBenchmarks.cs" />
     <Compile Include="TryConvertToBenchmarks.cs" />
+    <Compile Include="TypeFinderBenchmarks.cs" />
     <Compile Include="XmlBenchmarks.cs" />
   </ItemGroup>
   <ItemGroup>
diff --git a/src/Umbraco.Tests/Cache/DeepCloneAppCacheTests.cs b/src/Umbraco.Tests/Cache/DeepCloneAppCacheTests.cs
index 3a504ad4e2..e4844cc6be 100644
--- a/src/Umbraco.Tests/Cache/DeepCloneAppCacheTests.cs
+++ b/src/Umbraco.Tests/Cache/DeepCloneAppCacheTests.cs
@@ -13,6 +13,7 @@ using Umbraco.Core.Logging;
 using Umbraco.Core.Models;
 using Umbraco.Core.Models.Entities;
 using Umbraco.Tests.Collections;
+using Umbraco.Tests.TestHelpers;
 using Umbraco.Web.Cache;
 
 namespace Umbraco.Tests.Cache
@@ -28,7 +29,7 @@ namespace Umbraco.Tests.Cache
         public override void Setup()
         {
             base.Setup();
-            var typeFinder = new TypeFinder(Mock.Of<ILogger>());
+            var typeFinder = TestHelper.GetTypeFinder();
             _memberCache = new ObjectCacheAppCache(typeFinder);
 
             _provider = new DeepCloneAppCache(_memberCache);
diff --git a/src/Umbraco.Tests/Cache/HttpRequestAppCacheTests.cs b/src/Umbraco.Tests/Cache/HttpRequestAppCacheTests.cs
index b9c948c1de..dbda6fb429 100644
--- a/src/Umbraco.Tests/Cache/HttpRequestAppCacheTests.cs
+++ b/src/Umbraco.Tests/Cache/HttpRequestAppCacheTests.cs
@@ -16,7 +16,7 @@ namespace Umbraco.Tests.Cache
         public override void Setup()
         {
             base.Setup();
-            var typeFinder = new TypeFinder(Mock.Of<ILogger>());
+            var typeFinder = TestHelper.GetTypeFinder();
             _ctx = new FakeHttpContextFactory("http://localhost/test");
             _appCache = new HttpRequestAppCache(() => _ctx.HttpContext.Items, typeFinder);
         }
diff --git a/src/Umbraco.Tests/Cache/ObjectAppCacheTests.cs b/src/Umbraco.Tests/Cache/ObjectAppCacheTests.cs
index 772e92cabe..7957026ad8 100644
--- a/src/Umbraco.Tests/Cache/ObjectAppCacheTests.cs
+++ b/src/Umbraco.Tests/Cache/ObjectAppCacheTests.cs
@@ -1,10 +1,7 @@
-using System.Collections.Generic;
-using System.Linq;
-using Moq;
+using System.Linq;
 using NUnit.Framework;
 using Umbraco.Core.Cache;
-using Umbraco.Core.Composing;
-using Umbraco.Core.Logging;
+using Umbraco.Tests.TestHelpers;
 
 namespace Umbraco.Tests.Cache
 {
@@ -21,7 +18,7 @@ namespace Umbraco.Tests.Cache
         public override void Setup()
         {
             base.Setup();
-            var typeFinder = new TypeFinder(Mock.Of<ILogger>());
+            var typeFinder = TestHelper.GetTypeFinder();
             _provider = new ObjectCacheAppCache(typeFinder);
         }
 
diff --git a/src/Umbraco.Tests/Components/ComponentTests.cs b/src/Umbraco.Tests/Components/ComponentTests.cs
index bef72e5fb7..7dc6025b0a 100644
--- a/src/Umbraco.Tests/Components/ComponentTests.cs
+++ b/src/Umbraco.Tests/Components/ComponentTests.cs
@@ -32,7 +32,7 @@ namespace Umbraco.Tests.Components
             var mock = new Mock<IFactory>();
 
             var logger = Mock.Of<ILogger>();
-            var typeFinder = new TypeFinder(logger);
+            var typeFinder = TestHelper.GetTypeFinder();
             var f = new UmbracoDatabaseFactory(logger, new Lazy<IMapperCollection>(() => new MapperCollection(Enumerable.Empty<BaseMapper>())), TestHelper.GetConfigs(), TestHelper.DbProviderFactoryCreator);
             var fs = new FileSystems(mock.Object, logger, TestHelper.IOHelper, SettingsForTests.GenerateMockGlobalSettings());
             var coreDebug = Mock.Of<ICoreDebug>();
@@ -371,14 +371,15 @@ namespace Umbraco.Tests.Components
         public void AllComposers()
         {
             var ioHelper = TestHelper.IOHelper;
-            var typeFinder = new TypeFinder(Mock.Of<ILogger>());
+            var typeFinder = TestHelper.GetTypeFinder();
             var typeLoader = new TypeLoader(ioHelper, typeFinder, AppCaches.Disabled.RuntimeCache, new DirectoryInfo(ioHelper.MapPath("~/App_Data/TEMP")), Mock.Of<IProfilingLogger>());
 
             var register = MockRegister();
             var composition = new Composition(register, typeLoader, Mock.Of<IProfilingLogger>(),
                 MockRuntimeState(RuntimeLevel.Run), Configs, TestHelper.IOHelper, AppCaches.NoCache);
 
-            var types = typeLoader.GetTypes<IComposer>().Where(x => x.FullName.StartsWith("Umbraco.Core.") || x.FullName.StartsWith("Umbraco.Web"));
+            var allComposers = typeLoader.GetTypes<IComposer>().ToList();
+            var types = allComposers.Where(x => x.FullName.StartsWith("Umbraco.Core.") || x.FullName.StartsWith("Umbraco.Web")).ToList();
             var composers = new Composers(composition, types, Enumerable.Empty<Attribute>(), Mock.Of<IProfilingLogger>());
             var requirements = composers.GetRequirements();
             var report = Composers.GetComposersReport(requirements);
diff --git a/src/Umbraco.Tests/Composing/ComposingTestBase.cs b/src/Umbraco.Tests/Composing/ComposingTestBase.cs
index ac7dd8be2a..6c5ccd5510 100644
--- a/src/Umbraco.Tests/Composing/ComposingTestBase.cs
+++ b/src/Umbraco.Tests/Composing/ComposingTestBase.cs
@@ -22,7 +22,7 @@ namespace Umbraco.Tests.Composing
         {
             ProfilingLogger = new ProfilingLogger(Mock.Of<ILogger>(), Mock.Of<IProfiler>());
 
-            var typeFinder = new TypeFinder(Mock.Of<ILogger>());
+            var typeFinder = TestHelper.GetTypeFinder();
             var ioHelper = TestHelper.IOHelper;
             TypeLoader = new TypeLoader(ioHelper, typeFinder, NoAppCache.Instance, new DirectoryInfo(ioHelper.MapPath("~/App_Data/TEMP")), ProfilingLogger, false, AssembliesToScan);
         }
diff --git a/src/Umbraco.Tests/Composing/CompositionTests.cs b/src/Umbraco.Tests/Composing/CompositionTests.cs
index 4dfaf6871d..ce3cdfac17 100644
--- a/src/Umbraco.Tests/Composing/CompositionTests.cs
+++ b/src/Umbraco.Tests/Composing/CompositionTests.cs
@@ -38,7 +38,7 @@ namespace Umbraco.Tests.Composing
                 .Returns(() => factoryFactory?.Invoke(mockedFactory));
 
             var logger = new ProfilingLogger(Mock.Of<ILogger>(), Mock.Of<IProfiler>());
-            var typeFinder = new TypeFinder(Mock.Of<ILogger>());
+            var typeFinder = TestHelper.GetTypeFinder();
             var ioHelper = TestHelper.IOHelper;
             var typeLoader = new TypeLoader(ioHelper, typeFinder, Mock.Of<IAppPolicyCache>(), new DirectoryInfo(ioHelper.MapPath("~/App_Data/TEMP")), logger);
             var composition = new Composition(mockedRegister, typeLoader, logger, Mock.Of<IRuntimeState>(), TestHelper.GetConfigs(), TestHelper.IOHelper, AppCaches.NoCache);
diff --git a/src/Umbraco.Tests/Composing/TypeFinderTests.cs b/src/Umbraco.Tests/Composing/TypeFinderTests.cs
index 5fe4c241d6..3bdfd09752 100644
--- a/src/Umbraco.Tests/Composing/TypeFinderTests.cs
+++ b/src/Umbraco.Tests/Composing/TypeFinderTests.cs
@@ -57,7 +57,7 @@ namespace Umbraco.Tests.Composing
         [Test]
         public void Find_Class_Of_Type_With_Attribute()
         {
-            var typeFinder = new TypeFinder(GetTestProfilingLogger());
+            var typeFinder = new TypeFinder(GetTestProfilingLogger(), new DefaultUmbracoAssemblyProvider(GetType().Assembly));
             var typesFound = typeFinder.FindClassesOfTypeWithAttribute<TestEditor, MyTestAttribute>(_assemblies);
             Assert.AreEqual(2, typesFound.Count());
         }
@@ -65,12 +65,15 @@ namespace Umbraco.Tests.Composing
         [Test]
         public void Find_Classes_With_Attribute()
         {
-            var typeFinder = new TypeFinder(GetTestProfilingLogger());
+            var typeFinder = new TypeFinder(GetTestProfilingLogger(), new DefaultUmbracoAssemblyProvider(GetType().Assembly));
             var typesFound = typeFinder.FindClassesWithAttribute<TreeAttribute>(_assemblies);
             Assert.AreEqual(0, typesFound.Count()); // 0 classes in _assemblies are marked with [Tree]
 
             typesFound = typeFinder.FindClassesWithAttribute<TreeAttribute>(new[] { typeof (UmbracoContext).Assembly });
             Assert.AreEqual(22, typesFound.Count()); // + classes in Umbraco.Web are marked with [Tree]
+
+            typesFound = typeFinder.FindClassesWithAttribute<TreeAttribute>();
+            Assert.AreEqual(22, typesFound.Count()); // + classes in Umbraco.Web are marked with [Tree]
         }
 
         private static IProfilingLogger GetTestProfilingLogger()
diff --git a/src/Umbraco.Tests/Composing/TypeLoaderTests.cs b/src/Umbraco.Tests/Composing/TypeLoaderTests.cs
index 6658c689e1..d0181563a8 100644
--- a/src/Umbraco.Tests/Composing/TypeLoaderTests.cs
+++ b/src/Umbraco.Tests/Composing/TypeLoaderTests.cs
@@ -27,7 +27,7 @@ namespace Umbraco.Tests.Composing
         public void Initialize()
         {
             // this ensures it's reset
-            var typeFinder = new TypeFinder(Mock.Of<ILogger>());
+            var typeFinder = TestHelper.GetTypeFinder();
             _typeLoader = new TypeLoader(TestHelper.IOHelper, typeFinder, NoAppCache.Instance,
                 new DirectoryInfo(TestHelper.IOHelper.MapPath("~/App_Data/TEMP")),
                 new ProfilingLogger(Mock.Of<ILogger>(), Mock.Of<IProfiler>()), false,
diff --git a/src/Umbraco.Tests/Macros/MacroTests.cs b/src/Umbraco.Tests/Macros/MacroTests.cs
index 66adfc4a97..d6ed8f33c2 100644
--- a/src/Umbraco.Tests/Macros/MacroTests.cs
+++ b/src/Umbraco.Tests/Macros/MacroTests.cs
@@ -17,7 +17,7 @@ namespace Umbraco.Tests.Macros
         [SetUp]
         public void Setup()
         {
-            var typeFinder = new TypeFinder(Mock.Of<ILogger>());
+            var typeFinder = TestHelper.GetTypeFinder();
             //we DO want cache enabled for these tests
             var cacheHelper = new AppCaches(
                 new ObjectCacheAppCache(typeFinder),
diff --git a/src/Umbraco.Tests/Models/ContentTests.cs b/src/Umbraco.Tests/Models/ContentTests.cs
index d5117c6a69..07b7ae7cba 100644
--- a/src/Umbraco.Tests/Models/ContentTests.cs
+++ b/src/Umbraco.Tests/Models/ContentTests.cs
@@ -22,6 +22,7 @@ using Umbraco.Tests.TestHelpers.Entities;
 using Umbraco.Tests.TestHelpers.Stubs;
 using Umbraco.Tests.Testing;
 using Umbraco.Web.PropertyEditors;
+using Umbraco.Tests.TestHelpers;
 
 namespace Umbraco.Tests.Models
 {
@@ -269,7 +270,8 @@ namespace Umbraco.Tests.Models
             content.UpdateDate = DateTime.Now;
             content.WriterId = 23;
 
-            var runtimeCache = new ObjectCacheAppCache(new TypeFinder(Mock.Of<ILogger>()));
+            var typeFinder = TestHelper.GetTypeFinder();
+            var runtimeCache = new ObjectCacheAppCache(typeFinder);
             runtimeCache.Insert(content.Id.ToString(CultureInfo.InvariantCulture), () => content);
 
             var proflog = GetTestProfilingLogger();
diff --git a/src/Umbraco.Tests/Published/PropertyCacheLevelTests.cs b/src/Umbraco.Tests/Published/PropertyCacheLevelTests.cs
index d3e6dae26b..769985d515 100644
--- a/src/Umbraco.Tests/Published/PropertyCacheLevelTests.cs
+++ b/src/Umbraco.Tests/Published/PropertyCacheLevelTests.cs
@@ -127,7 +127,7 @@ namespace Umbraco.Tests.Published
 
             var setType1 = publishedContentTypeFactory.CreateContentType(1000, "set1", CreatePropertyTypes);
 
-            var typeFinder = new TypeFinder(Mock.Of<ILogger>());
+            var typeFinder = TestHelper.GetTypeFinder();
             var elementsCache = new FastDictionaryAppCache(typeFinder);
             var snapshotCache = new FastDictionaryAppCache(typeFinder);
 
diff --git a/src/Umbraco.Tests/PublishedContent/NuCacheChildrenTests.cs b/src/Umbraco.Tests/PublishedContent/NuCacheChildrenTests.cs
index c1f571aa91..bea0dce979 100644
--- a/src/Umbraco.Tests/PublishedContent/NuCacheChildrenTests.cs
+++ b/src/Umbraco.Tests/PublishedContent/NuCacheChildrenTests.cs
@@ -143,7 +143,7 @@ namespace Umbraco.Tests.PublishedContent
             // create a data source for NuCache
             _source = new TestDataSource(kits);
 
-            var typeFinder = new TypeFinder(Mock.Of<ILogger>());
+            var typeFinder = TestHelper.GetTypeFinder();
             var settings = Mock.Of<INuCacheSettings>();
 
 
diff --git a/src/Umbraco.Tests/PublishedContent/NuCacheTests.cs b/src/Umbraco.Tests/PublishedContent/NuCacheTests.cs
index c5c2f678ee..7abd4179f0 100644
--- a/src/Umbraco.Tests/PublishedContent/NuCacheTests.cs
+++ b/src/Umbraco.Tests/PublishedContent/NuCacheTests.cs
@@ -184,7 +184,7 @@ namespace Umbraco.Tests.PublishedContent
             // create a variation accessor
             _variationAccesor = new TestVariationContextAccessor();
 
-            var typeFinder = new TypeFinder(Mock.Of<ILogger>());
+            var typeFinder = TestHelper.GetTypeFinder();
             var settings = Mock.Of<INuCacheSettings>();
 
             // at last, create the complete NuCache snapshot service!
diff --git a/src/Umbraco.Tests/Runtimes/CoreRuntimeTests.cs b/src/Umbraco.Tests/Runtimes/CoreRuntimeTests.cs
index e4d0e596ae..9fb77ef59d 100644
--- a/src/Umbraco.Tests/Runtimes/CoreRuntimeTests.cs
+++ b/src/Umbraco.Tests/Runtimes/CoreRuntimeTests.cs
@@ -125,6 +125,10 @@ namespace Umbraco.Tests.Runtimes
 
             }
 
+            // override because we cannot use Assembly.GetEntryAssembly in Nunit tests since that is always null
+            protected override ITypeFinder GetTypeFinder()
+                => new TypeFinder(Logger, new DefaultUmbracoAssemblyProvider(GetType().Assembly));
+
             // must override the database factory
             // else BootFailedException because U cannot connect to the configured db
             protected internal override IUmbracoDatabaseFactory GetDatabaseFactory()
diff --git a/src/Umbraco.Tests/Runtimes/StandaloneTests.cs b/src/Umbraco.Tests/Runtimes/StandaloneTests.cs
index 225506093e..2560ae8e94 100644
--- a/src/Umbraco.Tests/Runtimes/StandaloneTests.cs
+++ b/src/Umbraco.Tests/Runtimes/StandaloneTests.cs
@@ -63,7 +63,7 @@ namespace Umbraco.Tests.Runtimes
             var profilingLogger = new ProfilingLogger(logger, profiler);
             var appCaches = AppCaches.Disabled;
             var databaseFactory = new UmbracoDatabaseFactory(logger, new Lazy<IMapperCollection>(() => factory.GetInstance<IMapperCollection>()), TestHelper.GetConfigs(), TestHelper.DbProviderFactoryCreator);
-            var typeFinder = new TypeFinder(logger);
+            var typeFinder = new TypeFinder(logger, new DefaultUmbracoAssemblyProvider(GetType().Assembly));
             var ioHelper = TestHelper.IOHelper;
             var hostingEnvironment = Mock.Of<IHostingEnvironment>();
             var typeLoader = new TypeLoader(ioHelper, typeFinder, appCaches.RuntimeCache, new DirectoryInfo(ioHelper.MapPath("~/App_Data/TEMP")), profilingLogger);
@@ -256,7 +256,7 @@ namespace Umbraco.Tests.Runtimes
             var profilingLogger = new ProfilingLogger(logger, profiler);
             var appCaches = AppCaches.Disabled;
             var databaseFactory = Mock.Of<IUmbracoDatabaseFactory>();
-            var typeFinder = new TypeFinder(Mock.Of<ILogger>());
+            var typeFinder = TestHelper.GetTypeFinder();
             var ioHelper = TestHelper.IOHelper;
             var typeLoader = new TypeLoader(ioHelper, typeFinder, appCaches.RuntimeCache, new DirectoryInfo(ioHelper.MapPath("~/App_Data/TEMP")), profilingLogger);
             var runtimeState = Mock.Of<IRuntimeState>();
diff --git a/src/Umbraco.Tests/Scoping/ScopedNuCacheTests.cs b/src/Umbraco.Tests/Scoping/ScopedNuCacheTests.cs
index 7a388417bc..41c8d59105 100644
--- a/src/Umbraco.Tests/Scoping/ScopedNuCacheTests.cs
+++ b/src/Umbraco.Tests/Scoping/ScopedNuCacheTests.cs
@@ -85,7 +85,7 @@ namespace Umbraco.Tests.Scoping
             var memberRepository = Mock.Of<IMemberRepository>();
             var hostingEnvironment = TestHelper.GetHostingEnvironment();
 
-            var typeFinder = new TypeFinder(Mock.Of<ILogger>());
+            var typeFinder = TestHelper.GetTypeFinder();
             var settings = Mock.Of<INuCacheSettings>();
 
             return new PublishedSnapshotService(
diff --git a/src/Umbraco.Tests/Services/ContentTypeServiceVariantsTests.cs b/src/Umbraco.Tests/Services/ContentTypeServiceVariantsTests.cs
index 1b6b632a10..33e8b0010e 100644
--- a/src/Umbraco.Tests/Services/ContentTypeServiceVariantsTests.cs
+++ b/src/Umbraco.Tests/Services/ContentTypeServiceVariantsTests.cs
@@ -58,7 +58,7 @@ namespace Umbraco.Tests.Services
             var memberRepository = Mock.Of<IMemberRepository>();
             var hostingEnvironment = Mock.Of<IHostingEnvironment>();
 
-            var typeFinder = new TypeFinder(Mock.Of<ILogger>());
+            var typeFinder = TestHelper.GetTypeFinder();
             var settings = Mock.Of<INuCacheSettings>();
 
             return new PublishedSnapshotService(
diff --git a/src/Umbraco.Tests/TestHelpers/BaseUsingSqlCeSyntax.cs b/src/Umbraco.Tests/TestHelpers/BaseUsingSqlCeSyntax.cs
index 2bd36947c6..e035eaa807 100644
--- a/src/Umbraco.Tests/TestHelpers/BaseUsingSqlCeSyntax.cs
+++ b/src/Umbraco.Tests/TestHelpers/BaseUsingSqlCeSyntax.cs
@@ -38,7 +38,7 @@ namespace Umbraco.Tests.TestHelpers
 
             var ioHelper = TestHelper.IOHelper;
             var logger = new ProfilingLogger(Mock.Of<ILogger>(), Mock.Of<IProfiler>());
-            var typeFinder = new TypeFinder(Mock.Of<ILogger>());
+            var typeFinder = TestHelper.GetTypeFinder();
             var typeLoader = new TypeLoader(ioHelper, typeFinder, NoAppCache.Instance,
                 new DirectoryInfo(ioHelper.MapPath("~/App_Data/TEMP")),
                 logger,
diff --git a/src/Umbraco.Tests/TestHelpers/Stubs/TestControllerFactory.cs b/src/Umbraco.Tests/TestHelpers/Stubs/TestControllerFactory.cs
index c79a0f5c47..f5d18e05ba 100644
--- a/src/Umbraco.Tests/TestHelpers/Stubs/TestControllerFactory.cs
+++ b/src/Umbraco.Tests/TestHelpers/Stubs/TestControllerFactory.cs
@@ -40,7 +40,7 @@ namespace Umbraco.Tests.TestHelpers.Stubs
         {
             if (_factory != null) return _factory(requestContext);
 
-            var typeFinder = new TypeFinder(Mock.Of<ILogger>());
+            var typeFinder = TestHelper.GetTypeFinder();
             var types = typeFinder.FindClassesOfType<ControllerBase>(new[] { Assembly.GetExecutingAssembly() });
 
             var controllerTypes = types.Where(x => x.Name.Equals(controllerName + "Controller", StringComparison.InvariantCultureIgnoreCase));
diff --git a/src/Umbraco.Tests/TestHelpers/TestHelper.cs b/src/Umbraco.Tests/TestHelpers/TestHelper.cs
index 309ba9a5fc..b201959de6 100644
--- a/src/Umbraco.Tests/TestHelpers/TestHelper.cs
+++ b/src/Umbraco.Tests/TestHelpers/TestHelper.cs
@@ -43,6 +43,14 @@ namespace Umbraco.Tests.TestHelpers
     public static class TestHelper
     {
 
+        public static ITypeFinder GetTypeFinder()
+        {
+            
+            var typeFinder = new TypeFinder(Mock.Of<ILogger>(),                
+                new DefaultUmbracoAssemblyProvider(typeof(TestHelper).Assembly));
+            return typeFinder;
+        }
+
         public static TypeLoader GetMockedTypeLoader()
         {
             return new TypeLoader(IOHelper, Mock.Of<ITypeFinder>(), Mock.Of<IAppPolicyCache>(), new DirectoryInfo(IOHelper.MapPath("~/App_Data/TEMP")), Mock.Of<IProfilingLogger>());
diff --git a/src/Umbraco.Tests/TestHelpers/TestObjects.cs b/src/Umbraco.Tests/TestHelpers/TestObjects.cs
index 2af409e024..bb342c9939 100644
--- a/src/Umbraco.Tests/TestHelpers/TestObjects.cs
+++ b/src/Umbraco.Tests/TestHelpers/TestObjects.cs
@@ -247,7 +247,7 @@ namespace Umbraco.Tests.TestHelpers
                 databaseFactory = new UmbracoDatabaseFactory(Constants.System.UmbracoConnectionName, logger, new Lazy<IMapperCollection>(() => mappers), TestHelper.GetConfigs(), TestHelper.DbProviderFactoryCreator);
             }
 
-            typeFinder = typeFinder ?? new TypeFinder(logger);
+            typeFinder = typeFinder ?? new TypeFinder(logger, new DefaultUmbracoAssemblyProvider(GetType().Assembly));
             fileSystems = fileSystems ?? new FileSystems(Current.Factory, logger, TestHelper.IOHelper, SettingsForTests.GenerateMockGlobalSettings());
             var coreDebug = Current.Configs.CoreDebug();
             var mediaFileSystem = Mock.Of<IMediaFileSystem>();
diff --git a/src/Umbraco.Tests/Testing/UmbracoTestBase.cs b/src/Umbraco.Tests/Testing/UmbracoTestBase.cs
index 41c05276fb..58a6fa6d41 100644
--- a/src/Umbraco.Tests/Testing/UmbracoTestBase.cs
+++ b/src/Umbraco.Tests/Testing/UmbracoTestBase.cs
@@ -171,7 +171,7 @@ namespace Umbraco.Tests.Testing
             var proflogger = new ProfilingLogger(logger, profiler);
             IOHelper = TestHelper.IOHelper;
 
-            TypeFinder = new TypeFinder(logger);
+            TypeFinder = new TypeFinder(logger, new DefaultUmbracoAssemblyProvider(GetType().Assembly));
             var appCaches = GetAppCaches();
             var globalSettings = SettingsForTests.GetDefaultGlobalSettings();
             var settings = SettingsForTests.GenerateMockWebRoutingSettings();
diff --git a/src/Umbraco.Tests/Web/UmbracoHelperTests.cs b/src/Umbraco.Tests/Web/UmbracoHelperTests.cs
index b479961896..62d7e941d7 100644
--- a/src/Umbraco.Tests/Web/UmbracoHelperTests.cs
+++ b/src/Umbraco.Tests/Web/UmbracoHelperTests.cs
@@ -28,7 +28,7 @@ namespace Umbraco.Tests.Web
         {
             // FIXME: bad in a unit test - but Udi has a static ctor that wants it?!
             var container = new Mock<IFactory>();
-            var typeFinder = new TypeFinder(Mock.Of<ILogger>());
+            var typeFinder = TestHelper.GetTypeFinder();
             var ioHelper = TestHelper.IOHelper;
             container
                 .Setup(x => x.GetInstance(typeof(TypeLoader)))
diff --git a/src/Umbraco.Web/Composing/BuildManagerTypeFinder.cs b/src/Umbraco.Web/Composing/BuildManagerTypeFinder.cs
deleted file mode 100644
index 994e8c26c4..0000000000
--- a/src/Umbraco.Web/Composing/BuildManagerTypeFinder.cs
+++ /dev/null
@@ -1,118 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.IO;
-using System.Linq;
-using System.Reflection;
-using System.Security;
-using System.Web.Compilation;
-using Umbraco.Core.Configuration;
-using Umbraco.Core.Composing;
-using Umbraco.Core.Configuration.UmbracoSettings;
-using Umbraco.Core.Hosting;
-using Umbraco.Core.IO;
-using Umbraco.Core.Logging;
-
-namespace Umbraco.Web.Composing
-{
-    /// <summary>
-    /// An implementation of TypeFinder that uses the BuildManager to resolve references for aspnet framework hosted websites
-    /// </summary>
-    /// <remarks>
-    /// This finder will also try to resolve dynamic assemblies created from App_Code
-    /// </remarks>
-    internal class BuildManagerTypeFinder : TypeFinder, ITypeFinder
-    {
-
-        public BuildManagerTypeFinder(
-            IIOHelper ioHelper,
-            IHostingEnvironment hostingEnvironment,
-            ILogger logger,
-            ITypeFinderConfig typeFinderConfig = null) : base(logger, typeFinderConfig)
-        {
-            if (ioHelper == null) throw new ArgumentNullException(nameof(ioHelper));
-            if (hostingEnvironment == null) throw new ArgumentNullException(nameof(hostingEnvironment));
-            if (logger == null) throw new ArgumentNullException(nameof(logger));
-
-            _allAssemblies = new Lazy<HashSet<Assembly>>(() =>
-            {
-                var isHosted = hostingEnvironment.IsHosted;
-                try
-                {
-                    if (isHosted)
-                    {
-                        var assemblies = new HashSet<Assembly>(BuildManager.GetReferencedAssemblies().Cast<Assembly>());
-
-                        //here we are trying to get the App_Code assembly
-                        var fileExtensions = new[] { ".cs", ".vb" }; //only vb and cs files are supported
-                        var appCodeFolder = new DirectoryInfo(ioHelper.MapPath(ioHelper.ResolveUrl("~/App_code")));
-                        //check if the folder exists and if there are any files in it with the supported file extensions
-                        if (appCodeFolder.Exists && fileExtensions.Any(x => appCodeFolder.GetFiles("*" + x).Any()))
-                        {
-                            try
-                            {
-                                var appCodeAssembly = Assembly.Load("App_Code");
-                                if (assemblies.Contains(appCodeAssembly) == false) // BuildManager will find App_Code already
-                                    assemblies.Add(appCodeAssembly);
-                            }
-                            catch (FileNotFoundException ex)
-                            {
-                                //this will occur if it cannot load the assembly
-                                logger.Error(typeof(TypeFinder), ex, "Could not load assembly App_Code");
-                            }
-                        }
-                    }
-                }
-                catch (InvalidOperationException e)
-                {
-                    if (e.InnerException is SecurityException == false)
-                        throw;
-                }
-
-                // Not hosted, just use the default implementation
-                return new HashSet<Assembly>(base.AssembliesToScan);
-            });
-        }
-
-        private readonly Lazy<HashSet<Assembly>> _allAssemblies;
-
-        /// <summary>
-        /// Explicitly implement and return result from BuildManager
-        /// </summary>
-        /// <param name="name"></param>
-        /// <returns></returns>
-        Type ITypeFinder.GetTypeByName (string name) => BuildManager.GetType(name, false);
-
-        /// <summary>
-        /// Explicitly implement and return result from BuildManager
-        /// </summary>
-        IEnumerable<Assembly> ITypeFinder.AssembliesToScan => _allAssemblies.Value;
-
-        /// <summary>
-        /// TypeFinder config via appSettings
-        /// </summary>
-        internal class TypeFinderConfig : ITypeFinderConfig
-        {
-            private readonly ITypeFinderSettings _settings;
-            private IEnumerable<string> _assembliesAcceptingLoadExceptions;
-
-            public TypeFinderConfig(ITypeFinderSettings settings)
-            {
-                _settings = settings;
-            }
-
-            public IEnumerable<string> AssembliesAcceptingLoadExceptions
-            {
-                get
-                {
-                    if (_assembliesAcceptingLoadExceptions != null)
-                        return _assembliesAcceptingLoadExceptions;
-
-                    var s = _settings.AssembliesAcceptingLoadExceptions;
-                    return _assembliesAcceptingLoadExceptions = string.IsNullOrWhiteSpace(s)
-                        ? Array.Empty<string>()
-                        : s.Split(',').Select(x => x.Trim()).ToArray();
-                }
-            }
-        }
-    }
-}
diff --git a/src/Umbraco.Web/Runtime/WebRuntime.cs b/src/Umbraco.Web/Runtime/WebRuntime.cs
index 582f35db70..ea08dc9135 100644
--- a/src/Umbraco.Web/Runtime/WebRuntime.cs
+++ b/src/Umbraco.Web/Runtime/WebRuntime.cs
@@ -21,8 +21,6 @@ namespace Umbraco.Web.Runtime
     /// <remarks>On top of CoreRuntime, handles all of the web-related runtime aspects of Umbraco.</remarks>
     public class WebRuntime : CoreRuntime
     {
-        private BuildManagerTypeFinder _typeFinder;
-
         /// <summary>
         /// Initializes a new instance of the <see cref="WebRuntime"/> class.
         /// </summary>
@@ -92,8 +90,6 @@ namespace Umbraco.Web.Runtime
 
         #region Getters
 
-        protected override ITypeFinder GetTypeFinder() => _typeFinder ?? (_typeFinder = new BuildManagerTypeFinder(IOHelper, HostingEnvironment, Logger, new BuildManagerTypeFinder.TypeFinderConfig(new TypeFinderSettings())));
-
         protected override AppCaches GetAppCaches() => new AppCaches(
                 // we need to have the dep clone runtime cache provider to ensure
                 // all entities are cached properly (cloned in and cloned out)
diff --git a/src/Umbraco.Web/Umbraco.Web.csproj b/src/Umbraco.Web/Umbraco.Web.csproj
index 504f36786a..df6233431a 100755
--- a/src/Umbraco.Web/Umbraco.Web.csproj
+++ b/src/Umbraco.Web/Umbraco.Web.csproj
@@ -143,7 +143,6 @@
     <Compile Include="Compose\AuditEventsComposer.cs" />
     <Compile Include="Compose\BackOfficeUserAuditEventsComponent.cs" />
     <Compile Include="Compose\BackOfficeUserAuditEventsComposer.cs" />
-    <Compile Include="Composing\BuildManagerTypeFinder.cs" />
     <Compile Include="Composing\CompositionExtensions\Installer.cs" />
     <Compile Include="Composing\LightInject\LightInjectContainer.cs" />
     <Compile Include="Models\NoNodesViewModel.cs" />