[Fusion] Add small collections improvement

src/HotChocolate/Fusion/src/Fusion.Execution/Execution/ExecutionState.cs

@@ -1,4 +1,5 @@
 using System.Collections.Concurrent;
+using System.Collections.Immutable;
 using System.Diagnostics.CodeAnalysis;
 using System.Runtime.CompilerServices;
 using HotChocolate.Fusion.Execution.Nodes;
@@ -164,9 +165,11 @@ public void CompleteNode(
         {
             if (result.DependentsToExecute.Length > 0)
             {
+                var dependentsToExecute = result.DependentsToExecute;
+
                 foreach (var dependent in node.Dependents)
                 {
-                    if (!result.DependentsToExecute.Contains(dependent))
+                    if (!ContainsDependent(dependentsToExecute, dependent))
                     {
                         SkipNode(context, dependent);
                     }
@@ -358,6 +361,23 @@ private bool IsInBacklog(int nodeId)
         => (uint)nodeId < (uint)_nodeStates.Length
             && _nodeStates[nodeId] == NodeStateBacklog;
 
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    private static bool ContainsDependent(
+        ImmutableArray<ExecutionNode> dependentsToExecute,
+        ExecutionNode dependent)
+    {
+        return dependentsToExecute.Length switch
+        {
+            1 => ReferenceEquals(dependentsToExecute[0], dependent),
+            2 => ReferenceEquals(dependentsToExecute[0], dependent)
+                || ReferenceEquals(dependentsToExecute[1], dependent),
+            3 => ReferenceEquals(dependentsToExecute[0], dependent)
+                || ReferenceEquals(dependentsToExecute[1], dependent)
+                || ReferenceEquals(dependentsToExecute[2], dependent),
+            _ => dependentsToExecute.Contains(dependent)
+        };
+    }
+
     private void AddToBacklog(ExecutionNode node)
     {
         var nodeId = node.Id;

src/HotChocolate/Fusion/src/Fusion.Execution/Execution/Nodes/Selection.cs

@@ -124,11 +124,13 @@ public bool IsIncluded(ulong includeFlags)
                 || (flags3 & includeFlags) == flags3;
         }
 
-        var span = _includeFlags.AsSpan();
+        var includeFlagsArray = _includeFlags;
 
-        for (var i = 0; i < span.Length; i++)
+        for (var i = 0; i < includeFlagsArray.Length; i++)
         {
-            if ((span[i] & includeFlags) == span[i])
+            var current = includeFlagsArray[i];
+
+            if ((current & includeFlags) == current)
             {
                 return true;
             }

src/HotChocolate/Fusion/src/Fusion.Execution/Execution/Nodes/SelectionSetLookup.cs

@@ -84,13 +84,7 @@ public static SelectionLookup Create(SelectionSet selectionSet)
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public bool TryGetSelection(ReadOnlySpan<byte> name, [NotNullWhen(true)] out Selection? selection)
     {
-        var table = _table.AsSpan();
-
-        if (table.Length == 0)
-        {
-            selection = default!;
-            return false;
-        }
+        var table = _table;
 
         var hashCode = ComputeHash(name, _seed);
         var index = hashCode & _mask;