Changes IndexFieldPolicies to be a StaticFieldCollection which is a keyed collection instead of using Linq and iterating to find the values in critical code

src/UmbracoExamine/StaticFieldCollection.cs

@@ -0,0 +1,23 @@
+using System.Collections.ObjectModel;
+
+namespace UmbracoExamine
+{
+    internal class StaticFieldCollection : KeyedCollection<string, StaticField>
+    {
+        protected override string GetKeyForItem(StaticField item)
+        {
+            return item.Name;
+        }
+
+        /// <summary>
+        /// Implements TryGetValue using the underlying dictionary
+        /// </summary>
+        /// <param name="key"></param>
+        /// <param name="field"></param>
+        /// <returns></returns>
+        public bool TryGetValue(string key, out StaticField field)
+        {
+            return Dictionary.TryGetValue(key, out field);
+        }
+    }
+}