I read a post titled "Improve Web Application Performance". I expected to have a lot of information to add, but it's actually pretty comprehensive. I recommend reading it if you're developing a web application. One of my biggest complaints about most websites is that they're way too slow. In this day and age there is really no reason for that.

Analog Stopwatch

The only other optimization I have used in the past that isn't mentioned in the post, is removing whitespace. While it can make your life a little harder because of some layout glitches it might cause (which are fixable), it can often have a pretty big effect on your page sizes. On one of my websites, I saw an average of a 10-20% decrease in page sizes, even when gzip compression was turned on.

The easiest way to remove whitespace from your pages is to use an HTTP module. One solution is available here for free. You simply add the binary DLL, and reference it in your web.config file. It couldn't hurt to give it a try the next time you're writing an ASP.NET application.