perf: replace LINQ dependency extraction with manual loop

TUnit.Engine/Building/Collectors/AotTestDataCollector.cs

@@ -269,7 +269,7 @@ private Task<TestMetadata> CreateMetadataFromDynamicDiscoveryResult(DynamicDisco
             TestName = testName,
             TestClassType = result.TestClassType,
             TestMethodName = methodInfo.Name,
-            Dependencies = result.Attributes.OfType<DependsOnAttribute>().Select(a => a.ToTestDependency()).ToArray(),
+            Dependencies = AttributeHelpers.ExtractDependencies(result.Attributes),
             DataSources = [], // Dynamic tests don't use data sources in the same way
             ClassDataSources = [],
             PropertyDataSources = [],

TUnit.Engine/Discovery/ReflectionTestDataCollector.cs

@@ -2229,7 +2229,7 @@ private Task<TestMetadata> CreateMetadataFromDynamicDiscoveryResult(DynamicDisco
             TestName = testName,
             TestClassType = result.TestClassType,
             TestMethodName = methodInfo.Name,
-            Dependencies = result.Attributes.OfType<DependsOnAttribute>().Select(static a => a.ToTestDependency()).ToArray(),
+            Dependencies = AttributeHelpers.ExtractDependencies(result.Attributes),
             DataSources = [], // Dynamic tests don't use data sources in the same way
             ClassDataSources = [],
             PropertyDataSources = [],
@@ -2248,6 +2248,7 @@ private Task<TestMetadata> CreateMetadataFromDynamicDiscoveryResult(DynamicDisco
         return Task.FromResult<TestMetadata>(metadata);
     }
 
+
     private static Attribute[] GetDynamicTestAttributes(DynamicDiscoveryResult result)
     {
         if (result.TestClassType == null)

TUnit.Engine/Helpers/AttributeHelpers.cs

@@ -0,0 +1,29 @@
+using TUnit.Core;
+
+namespace TUnit.Engine.Helpers;
+
+/// <summary>
+/// Shared attribute-extraction helpers used by the dynamic-discovery code paths
+/// (AOT, reflection, and runtime registration) so they stay in sync.
+/// </summary>
+internal static class AttributeHelpers
+{
+    /// <summary>
+    /// Extracts <see cref="TestDependency"/> entries from a materialised attribute list.
+    /// Returns the shared empty array when no <see cref="DependsOnAttribute"/> is present.
+    /// </summary>
+    public static TestDependency[] ExtractDependencies(List<Attribute> attributes)
+    {
+        List<TestDependency>? dependencies = null;
+
+        foreach (var attribute in attributes)
+        {
+            if (attribute is DependsOnAttribute dependsOn)
+            {
+                (dependencies ??= []).Add(dependsOn.ToTestDependency());
+            }
+        }
+
+        return dependencies?.ToArray() ?? [];
+    }
+}

TUnit.Engine/Services/TestRegistry.cs

@@ -285,9 +285,7 @@ private TestMetadata CreateMetadataFromDynamicDiscoveryResult(DynamicDiscoveryRe
             TestName = methodInfo.Name,
             TestClassType = result.TestClassType,
             TestMethodName = methodInfo.Name,
-            Dependencies = result.Attributes.OfType<DependsOnAttribute>()
-                .Select(x => x.ToTestDependency())
-                .ToArray(),
+            Dependencies = AttributeHelpers.ExtractDependencies(result.Attributes),
             DataSources = [],
             ClassDataSources = [],
             PropertyDataSources = [],