If you bought OS X Tiger thinking that Apple’s new Quartz 2D Extreme would accelerate your Powerbook, you were surely disappointed when you found out that Apple had shipped Tiger with Quartz 2D Extreme disabled!
Perhaps some day in a future 10.4 update Apple will eventually enable it, but for now, even if I enable it, the accelerated video only lasts a few minutes and then my Powerbook locks up solid. However, I did try a different form of video acceleration that does work. If you have an ATI video card, you can try overclocking it with ATIcceleratorII.
I have tried it on both my Powerbook and G4 desktop and the results are very stable and the boosted video speed helps with almost every application, including the Mac OS X Finder, which is very much needed.
Since this is a form of overclocking, you will want to make sure that you overclock only in small increments and that your computer is adequately cooled and not operating in high-temperature environment.
ATIcceleratorII can adjust both video memory and gpu speeds. You can find multiple user reports on Xlr8yourmac.com.