I use a thread for the UI display in WPF program(c#), but the CPU is high. I am not sure why

Question

I programming a c# code, I just used a thread to display a data on the UI, once per 100 ms. But I found the CPU(not the memory) is very high, from 20% to 70% immediately. Could someone else help me for this problem?

    public delegate void ThreadDisplayDelegate(string message);
    public ThreadDisplayDelegate _threaddelegate;
    public void DisplayCurrentDialog(string message)
    {
        if (_UI_receive.Dispatcher.CheckAccess())
        {
            _UI_receive.Text = message;
        }
        else
        {
            _UI_receive.Dispatcher.Invoke(_threaddelegate, message);
        }
    }
    public void ThreadUIDisplay()
    {
        _threaddelegate = new ThreadDisplayDelegate(DisplayCurrentDialog);
        while (_continue)
        {              
            DisplayCurrentDialog(_m_received_message);                
            System.Threading.Thread.Sleep(100);
        }
    }