Originally posted by azosx
You're wong. No, the GUI doesn't currently use the 3D hardware acceleration provided by most graphics cards like QE will, but it does use your graphics card in general for maginfying the Dock, scrolling webpages, resizing windows, watching DVD and using QT. Those are just a few examples, I'm sure there are many many many more.
Would you care to do a little test? I'll prove it.
Open up a Terminal window and type "top -u". (If you don't already know what this does, it sorts the top list by CPU usage.)
Now turn Dock magnification on, and constantly run your mouse up and down the Dock. (Make sure it's actually doing some magnifying that is make the icons small and the magnification size big.)
See how the process called "Window Manager" zooms up to 80% of the processor usage? At least it does on my mom's G3 iBook. It does the same (zooms up, don't remember the exact number) on my G4 cube at home.
Quartz Extreme stands to really improve OS X performance because the CPU handles all the GUI calculating currently. People who are using Jaguar report that this effect (described above) doesn't happen at all with computers that have Quartz Extreme enabled graphics cards. This proves that the CPU is the ONLY thing doing all the calculation (and if you ask any Apple engineer who is working on Mac OS X, I'll bet they'll tell you the exact same thing).
You can repeat this procedure and get the exact same results with any GUI operation. For example, if I resize a window or drag it around constantly in OmniWeb, OmniWeb's CPU usage shoots through the roof to 60% or so. Opening, scrolling through, and closing menus does the same thing too. If the graphics card had ANYTHING to do with calculating the GUI effects, you wouldn't see this dramatic increase in processor usage during simple operations like menu operation.
Oh, and by the way, I have a G4 Cube 450 MHz, and I tried out a 500 MHz Powerbook at the Palo Alto Apple Store opening. Let me tell you that the Powerbook was about on par with my G4 cube, and even a little faster in some respects. Window minimization (which is usually the real-world thing that I use to gauge a Mac's speed) was definitely better (enough to notice) on the Powerbook than on the G4 cube.
Lastly, no, the Powerbook G4 400 MHz does not come with 1 MB L2 cache. The Powerbook G4 _800_ MHz does. Nor does it come with inferior bus speeds. The G4 cube has a 100 MHz bus, and the Powerbook G4 has always had a 100 MHz bus.