After a lot of benchmarking i found the bottleneck for building the prop collection. Even though this new bottleneck is leaps and bounds faster than it was before... with this new fix it is epically fast

src/Umbraco.Web/WebServices/ExamineManagementApiController.cs

@@ -10,6 +10,7 @@ using Examine.LuceneEngine.Providers;
 using Examine.Providers;
 using Lucene.Net.Search;
 using Umbraco.Core;
+using Umbraco.Core.Logging;
 using Umbraco.Web.Search;
 using Umbraco.Web.WebApi;
 
@@ -121,6 +122,7 @@ namespace Umbraco.Web.WebServices
                 }
                 catch (Exception ex)
                 {
+                    LogHelper.Error<ExamineManagementApiController>("An error occurred rebuilding index", ex);
                     var response = Request.CreateResponse(HttpStatusCode.Conflict);
                     response.Content = new StringContent(string.Format("The index could not be rebuilt at this time, most likely there is another thread currently writing to the index. Error: {0}", ex));
                     response.ReasonPhrase = "Could Not Rebuild";