了解page页面的生命周期，对输出页面加载时间就非常简单了。

        protected DateTime dt; 
        protected void Page_Load(object sender, EventArgs e) 
        { 
              
        } 
        protected override void OnPreInit(EventArgs e) 
        { 
            dt = DateTime.Now; 
            base.OnPreInit(e); 
        } 
        protected override void OnLoadComplete(EventArgs e) 
        { 
            base.OnLoadComplete(e); 
            TimeSpan ts = DateTime.Now - dt; 
            Response.Write("加载页面用时：" + ts.TotalMilliseconds); 
        }