I'm having a hard time visualizing what's happening here. For example, when you place the cursor over Start>Programs, it takes a long time for all the icons and folders to load?

Not over Start>Programs, because that's just a parent folder of other folders. The problem always happens at the next level down, where I've got a menu full of programs with different icons. Often, one of those icons isn't in the icon cache, and has to be re-loaded before the menu will fully render and be clickable.

I've created an animated GIF file illustrating the problem. Click here to view it.