如何确定页面加载时的瓶颈？

I have a page that uses jQuery UI, and calls the datepicker on 2 different text boxes. Without the calls, ie. just loading the page without attaching any datepickers, the page loads in 1.20 seconds. With the datepickers attached, the page loads in 3.92 seconds. (this is in firefox)I have a page that uses jQuery UI, and calls th