C#调用多线程时间延长

  

  Stopwatch stw = new Stopwatch();


        public  int i = 0;
     private void Form1_Load(object sender, EventArgs e)
        {
            CheckForIllegalCrossThreadCalls = false;
            stw.Start();
            Thread thread = new Thread(start);
            thread.Start();
            for (int j = 0; j < 999999999; j++)
            {
                i++;
                if (i >= 99999999)
                {
                    stw.Stop();

                    label1.Text = stw.ElapsedMilliseconds.ToString();
                    break;
                }
            }
            //Suodeshuijisuan(Class1.shuiqian, Class1.shuilv, Class1.suodeshui);
            //label1.Text = "cd";
        }
        public void start()
        {
            for (int j = 0; j < 999999999; j++)
            {
                i++;
                if (i >= 99999999)
                {
                    stw.Stop();

                    label1.Text = stw.ElapsedMilliseconds.ToString();
                    break;
                }
            }
        }