Update

Author: JamesNK

src/Servers/Kestrel/perf/Kestrel.Performance/Http2ConnectionBenchmarkBase.cs

@@ -40,7 +40,6 @@ public abstract class Http2ConnectionBenchmarkBase
 
         protected abstract Task ProcessRequest(HttpContext httpContext);
 
-        [GlobalSetup]
         public virtual void GlobalSetup()
         {
             _memoryPool = SlabMemoryPoolFactory.Create();

src/Servers/Kestrel/perf/Kestrel.Performance/Http2ConnectionEmptyBenchmark.cs

@@ -14,8 +14,10 @@ public class Http2ConnectionBenchmark : Http2ConnectionBenchmarkBase
 
         private string _responseData;
 
+        [GlobalSetup]
         public override void GlobalSetup()
         {
+            base.GlobalSetup();
             _responseData = new string('!', ResponseDataLength);
         }
 

src/Servers/Kestrel/perf/Kestrel.Performance/Http2ConnectionHeadersBenchmark.cs

@@ -10,18 +10,32 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Performance
     public class Http2ConnectionHeadersBenchmark : Http2ConnectionBenchmarkBase
     {
         [Params(1, 4, 32)]
-        public int CustomHeaders { get; set; }
+        public int HeadersCount { get; set; }
 
         [Params(true, false)]
         public bool HeadersChange { get; set; }
 
         private int _headerIndex;
+        private string[] _headerNames;
+
+        [GlobalSetup]
+        public override void GlobalSetup()
+        {
+            base.GlobalSetup();
+
+            _headerNames = new string[HeadersCount * (HeadersChange ? 1000 : 1)];
+            for (var i = 0; i < _headerNames.Length; i++)
+            {
+                _headerNames[i] = "CustomHeader" + i;
+            }
+        }
 
         protected override Task ProcessRequest(HttpContext httpContext)
         {
-            for (var i = 0; i < CustomHeaders; i++)
+            for (var i = 0; i < HeadersCount; i++)
             {
-                httpContext.Response.Headers["CustomHeader" + _headerIndex] = "The quick brown fox jumps over the lazy dog.";
+                var headerName = _headerNames[_headerIndex % HeadersCount];
+                httpContext.Response.Headers[headerName] = "The quick brown fox jumps over the lazy dog.";
                 if (HeadersChange)
                 {
                     _headerIndex++;