I found one simple yet effective hint to speed up IIS requests processing when I've been merging several PHP application to IIS server from Linux hosting. Result is as good as both common caching and compression.
We need “Default Document” section from web node tabs.
Default list order is pretty dumb: php and aspx files are at the bottom.
Although this list is tiny changing its order and moving index.php up led to multiplied page load speed increase: from one or even several seconds of waiting before page load even starts to unnoticeable milliseconds. That's on dedicated virtual server.
I made no further test for ASP.NET application and I always move Document.aspx up when setting up new web node (that's on IIS 6 BTW, so better change order on my IIS 7 servers…). But the same trick should do for ASP.NET as well as the whole problem is on server side, not on application.
Checked only on IIS7.