I tend to turn off the annoying Windows visual effects that make simple tasks take longer, especially fade-in and fade-out menus. Disabling such effects might only save me a small fraction of a second here or there, but it saves me a lot of frustration. I just can't stand waiting for an operating system to catch up with me. For the most part, I think the Apple UI engineers probably feel the same way, hence the increased baseline processor and RAM requirements for Leopard (867 MHz G4, 512 MB) as compared to Tiger (G3 systems with built-in FireWirewhich included a 300 MHz G3and 256 MB RAM).
Heck, in a way I almost think that Apple was being generious to G3 owners with Tiger's requirements; the Dashboard takes ridiculously long to launch on my 400 MHz G3 with 704 MB RAM, and searching with Spotlight takes forever, too. Incidentally, I've always figured that the only reason Apple let the Blue & White G3 run Tiger is that the original PowerMac G4 used the same hardware as the B&W, and Apple wanted to support all G4 systems. As soon as I saw Time Machine demonstrated, I was pretty darn sure that Apple would ax support for all G3 systems.