C#关于侦听本地端口：关闭被侦听的端口后界面卡

由于项目的特殊需要创建了两个TCP通道，一个用于连接服务器发送数据，一个用于侦听本机端口接收数据，在接收完数据后关闭本机被侦听的端口，窗体突然间很卡，需要很长时间才可以响应下一个窗体，请问该怎么解决？代码如下
侦听本地端口  接收数据：
delegate void aa();
        TcpListener TcpListener = null;
        TcpClient TcpClient = null;
        NetworkStream MyStream = null;
         /// <summary>
        /// 监听9806端口
        /// </summary>
        private void StartListen()
        {
            this.TcpListener = new TcpListener(9806);
            this.TcpListener.Start();
            TcpClient = this.TcpListener.AcceptTcpClient();
             MyStream = TcpClient.GetStream();
            while (true)
            {
                try
                {
                    byte[] bytes = new byte[2048];
                    int bytesRead = MyStream.Read(bytes, 0, bytes.Length);
                    string msg = System.Text.Encoding.UTF8.GetString(bytes, 0, bytesRead);
                    string[] su1 = msg.Split(new char[] { '/' });
                    if (msg != "")
                    {
                        aa a = delegate()
                        {
                            Dictionary<int, string> dic = new Dictionary<int, string>();
                            int i = 1;
                            foreach (string s in su1)
                            {
                                dic.Add(i, s.ToString());
                                i = i + 1;

                            }
                         }
                      }
                  }catch (Exception ex) {}
                }
关闭被侦听的端口
private void button1_Click_1(object sender, EventArgs e)
        {
            MyStream.Close();
            client.Close();
            TcpClient.Close();
            this.TcpListener.Stop();
        } --------------------编程问答-------------------- 额，可以先用tcpListener.Server.Shutdown(SocketShutdown.Both);这个方法禁止数据的收发。再关闭Socket。。

补充：.NET技术 ,  C#