perf: reduce allocations in EventReceiverOrchestrator and TestContextExtensions

TUnit.Engine/Extensions/TestContextExtensions.cs

@@ -148,11 +148,10 @@ private static T[] SortAndFilter<T>(List<T>? receivers) where T : class, IEventR
         }
 
         // Sort by Order
-        receivers.Sort((a, b) => a.Order.CompareTo(b.Order));
+        receivers.Sort(static (a, b) => a.Order.CompareTo(b.Order));
 
-        // Apply scoped attribute filtering and return as array
-        var filtered = ScopedAttributeFilter.FilterScopedAttributes(receivers);
-        return filtered.ToArray();
+        // Apply scoped attribute filtering - FilterScopedAttributes already returns T[]
+        return ScopedAttributeFilter.FilterScopedAttributes(receivers);
     }
 
     public static IEnumerable<object> GetEligibleEventObjects(this TestContext testContext)

TUnit.Engine/Services/EventReceiverOrchestrator.cs

@@ -287,13 +287,17 @@ private static async Task InvokeTestDiscoveryEventReceiversCoreAsync(ITestDiscov
 
     public async ValueTask InvokeHookRegistrationEventReceiversAsync(HookRegisteredContext hookContext, CancellationToken cancellationToken)
     {
-        // Filter scoped attributes to ensure only the highest priority one of each type is invoked
+        // Pre-sort by Order before filtering so that FilterScopedAttributes (which uses TryAdd
+        // and keeps the first encountered item per ScopeType) retains the lowest-Order attribute.
+        // After filtering, sort the result in-place for final invocation order.
         var filteredReceivers = ScopedAttributeFilter.FilterScopedAttributes(
             hookContext.HookMethod.Attributes
                 .OfType<IHookRegisteredEventReceiver>()
-                .OrderBy(static r => r.Order));
+                .OrderBy(static x => x.Order));
 
-        foreach (var receiver in filteredReceivers.OrderBy(static r => r.Order))
+        Array.Sort(filteredReceivers, static (a, b) => a.Order.CompareTo(b.Order));
+
+        foreach (var receiver in filteredReceivers)
         {
             await receiver.OnHookRegistered(hookContext);
         }