winform里怎么通过线程开启新窗体

        private void Nullfun()
        {
            Thread.Sleep(5000);
        }

        
        private void timer1_Tick(object sender, EventArgs e)
        {
            Nullfun();
            Form2 f = new Form2();
            f.Show();
        }

这里的timer用的是System.Windows.Forms.Timer下的.用这个timer子窗体不会卡死,但是界面会.
但是如果换成System.Timers.Timer,子窗体启动后就会一直卡死.究竟怎么写才好呢
[解决办法]

            new Thread(() =>
            {
                Thread.Sleep(5000);
                Application.Run(new Form2());
            }).Start();