Little Known Secrete ” UpdatePanel causes Postbacks”.

Even though it is good entry point in to AJAX programming using .NET technologies, UpdatePanel does not give you much performance over traditional PostBack model.

When used, UpdatePanel causes the postback similar to the traditional postback, instantiates the control tree, and at render time realizes to send only the required response (the content in the updatepanel).

So, apart from the reduced response bandwidth and nice looking flicker free UI, updatepanel is not really getting you much performance.

Having said that, i am sure you can get away with UpdatePanel for most of your needs.

I would try to supplement this with more information.