C#异步多线程ping,该如何解决

C#异步多线程ping

   private void button3_Click(object sender, EventArgs e)

        {

           

                //IPAddress address = IPAddress.Parse(Convert.ToString(dataGridView1.Rows[i].Cells[1].Value));

                Thread thread = new Thread(new ThreadStart(_pingThread));

                thread.IsBackground = true;

                thread.Start();

           

        }



        private void _pingThread()

        {


            Ping ping = new Ping();

            ping.PingCompleted += new PingCompletedEventHandler(_myPing_PingCompleted);            


            for(int i = 0; i < dataGridView1.Rows.Count; i++)

            {

                if (Convert.ToString(dataGridView1.Rows[i].Cells[1].Value) != "")

                {

                    string _ipAddress = Convert.ToString(dataGridView1.Rows[i].Cells[1].Value);

                    //每一行的datagridview中的第二格都有IP地址

                    PingReply result = ping.Send(_ipAddress);


                     if (result.Status != IPStatus.Success)

                      {

                          dataGridView1.Rows[i].Cells[3].Value = result.RoundtripTime.ToString();   

                       }

                }

            }



            

        }

求指导，我现在这个是多线程ping了吧，为啥我这个ping多个地址很慢的，，，别人做出的程序ping多个地址很快。。而我的没效率啊。。求改进。。。
------解决思路----------------------
首先每必要用多线程，再者这都不是异步，异步用Ping.SendAsync而不是Ping.Send
------解决思路----------------------
SendAsync