When the value is equal to the maxvalue, the progress of the progress bar is not at all

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.NET

WinForms

when the Value property is equal to the Maxvalue propterty ,the progress of the progress bar is not 100%.Does the progressbar react slowly?
i do not know why.

private void button1_Click(object sender, EventArgs e)
{
    f.Show();
    f.Visible = false;
    f.Show();
    f.Visible = false;
    new Thread(new ThreadStart(FunGo)).Start();
    f.ShowDialog(this);
}

Form1 f = new Form1();
private void FunGo()
{
    int i = 0;
    while (true)
    {
        f.Invoke(new MethodInvoker(delegate()
        {
            if(i<=100)
                f.Listen(i, 100);
        }));
        if (i == 100)
        {
            f.Invoke(new MethodInvoker(delegate()
            {
                f.Close();//when the progress ba does not show 100% ,the Form (f) closes
            }));
            break;
        }

        Thread.Sleep(100);
        i++;
    }
}