Final piece to the puzzle for U4-2571 Need to optimize empty recycle bin. Needed to hack around the ordering of items in the recycle bin because of the self-referencing constraint - parentID to id in the umbracoNode table by updating all parentID entries, which bypasses any reference issues with the foreignkey.

src/Umbraco.Core/Persistence/Repositories/RecycleBinRepository.cs

@@ -56,6 +56,7 @@ namespace Umbraco.Core.Persistence.Repositories
                               FormatDeleteStatement("cmsContentVersion", "ContentId"),
                               FormatDeleteStatement("cmsContentXml", "nodeID"),
                               FormatDeleteStatement("cmsContent", "NodeId"),
+                              "UPDATE umbracoNode SET parentID = '-20' WHERE trashed = '1' AND nodeObjectType = @NodeObjectType",
                               "DELETE FROM umbracoNode WHERE trashed = '1' AND nodeObjectType = @NodeObjectType"
                           };