One of the most (or the most) common use MS-AJAX control is the UpdatePanel. It let us send data to the server and get response asyc, and change part of the page without refreshing the page, and it give us faster and more nice user interaction. Altho it sound perfect, it have big limitation. While compressing the page, remove white spaces in the HTML and make our page very light, it is impossible to modify the response for the update panel. In every method (in the Render event or any Handler/Module) that we made that modify the response, we must exclude the respose that made by the UpdatePanel. The result is that we have a page with UpdatePanel that refreh a part of the page, we compressed the page and made it very light (lets say we compressed it from 30Kb to 5Kb). When we click the button that activate the update panel, it send the update panel request and receive its response, but this response is not compressed and can be sometimes even bigger than the complete page (that was compressed). It's a big contradiction!
There is a small thing we can do, it's really small, but better than nothing. The response for the UpdatePanel is build base on the original ASPX (before any compression), so, what we can do is, to optimize our original ASPX by removing any whitespaces. That will make the UpdatePanel response a little smaller.
What I use to do, is publish the site, and before uploading the files to the server, I optimize the ASPX files that have any UpdatePanel.
It is realy not big, but it is something.
In the bottom, you can download a tool I made to remove the white spaces from the ASPX and optimize it. Just copy your ASPX code and click optimize, and save that optimized code.
OptimizeASPX.exe (20.00 kb)