Set a threshold on when filtering moves to parallel

Author: jschick04

src/EventLogExpert.UI/Services/FilterService.cs

@@ -40,6 +40,16 @@ public IReadOnlyList<DisplayEventModel> GetFilteredEvents(
             return events as IReadOnlyList<DisplayEventModel> ?? [.. events];
         }
 
+        // For small collections, PLINQ's thread scheduling overhead exceeds the
+        // parallelism benefit. Use sequential filtering below the threshold.
+        if (events is IReadOnlyCollection<DisplayEventModel> { Count: < 10_000 } collection)
+        {
+            return collection
+                .Where(e => e.FilterByDate(eventFilter.DateFilter)
+                    .Filter(eventFilter.Filters, IsXmlEnabled))
+                .ToList();
+        }
+
         return events.AsParallel()
             .Where(e => e.FilterByDate(eventFilter.DateFilter)
                 .Filter(eventFilter.Filters, IsXmlEnabled))