当Fiddler开放时为什么请求速度增长？

Question

我使用压力测试工具，用C＃编写

许多任务并行运行，标准结果为每秒40-50次请求。 但是当我打开Fiddler时 - 请求增长到~300-500并且服务器处理它。

noFiddler变体的瓶颈在哪里？

简单任务

    public class PersonListTask : LTask
    {
        public override string Path => "/person/list?query={page: 1, pageSize: 30}";
        public override string Method => "GET";

        public override async Task ProcessAsync(IUserContext context)
        {
            var request = CreateRequestForContext(context); //WebRequest

            var response = await request.GetResponseAsync();

            if (response == null)
                throw new Exception("Responce null");

            var responceStream = new StreamReader(response.GetResponseStream(), Encoding.UTF8);

            responceStream.ReadToEnd();

            Interlocked.Increment(ref RequestCount);
        }
    }

     ..........
     ..........

     //running 
     private async Task Task_Function(IUserContext context)
     {
            while (true)
            {
                await Task.WhenAll(LTaskCollection.Tasks.Select(x => x.ProcessAsync(context)));
            }
      }