To speed up window redrawing, just use Tinkertool (see Hall of Fame at left) to turn the desktop off.
On a 8600 G3 547MHz with 256MB of RAM, ATI XclaimVR 128, and an Acard/66 with two 60GB drives, it made a significat difference in window redraws under very heavy load. Instead of graphics sort of crawling across the screen, they tend to pop up. Also less swapping on the second drive with the swapfile located on it. Limewire, dnet, iTunes, and Mozilla all running simultaneously. Other tips were used previously such as the disabled font smoothing and swapcop etc.
On a Sawtooth 450 with 384MB's of RAM, disabling the desktop made a small difference, but it was fast already.
[Editor's note: I have not tested this myself to verify any speed gains from disabling the desktop, but it makes sense. Then again, I like my desktop pictures too much to disable them!]
Mac OS X Hints
http://hints.macworld.com/article.php?story=2002043002152992