slowing-proxy.cs

 static void Proxy()
 {
     var tcpListener = new TcpListener(IPAddress.Loopback, 9000);
     tcpListener.Start();
     var buffer = new byte[1024];
     while (true)
     {
         var incomingConnection = tcpListener.AcceptTcpClient();
         var tcpClient = new TcpClient();
         tcpClient.Connect(IPAddress.Loopback, 9999);
         using (var recv = incomingConnection.GetStream())
         using (var send = tcpClient.GetStream())
         {
             while (true)
             {
                 var read = recv.Read(buffer, 0, 1024);
                 if (read == 0)
                     break;
                 Thread.Sleep(1);
                 send.Write(buffer, 0, read);
             }
         }
     }
 }