I ran into a well-known, but odd IE6 caching bug this week. If caching is turned off for IE6 browsers, modifying DOM elements triggers the browser to reload any resources referenced by the changed elements. So if a script changes the class name of 5 elements and the CSS classes have a background image property, then the background image will be reloaded once for each DOM update. This sucks the performance out of a web application.

There are several work arounds, but the best I’ve found is a simple IE6 Javascipt toggle that turns off the behaviour.