C# for循环求助
一段简单的代码如下

private void button1_Click(object sender, EventArgs e)
{
for (int i = 0; i < 2000000; i++)
{
this.progressBar1.Maximum = 2000000;
this.progressBar1.Value = i;
}
}
在VS2005里跑大概5秒，在VS2010里跑需要90秒左右，这是为什么？？？

protected void Button1_Click(object sender, EventArgs e)
        {
            Literal1.Text = DateTime.Now.ToString();

            int max = 0;
            for (int i = 0; i < 2000000; i++)
            {
                max =  i;
            }
            Literal1.Text += "    " + max+"    " + DateTime.Now.ToString();
        }