First post!
Regarding the improvements in Quartz Extreme... it's definitely been optimized, so the GUI runs faster in Tiger than Panther, even on older Macs. However the work is still done on the CPU rather than the GPU.
The GPU-based rendering is something additional, called Quartz 2D Extreme. That (in theory) will dramatically improve performance because it offloads just about everything to the GPU-- and this is where you need one of the video cards that supports it.
The thing to note is that Quartz 2D Extreme is turned off by default in Tiger. Apple left it disabled because it still has issues-- for example, enabling it causes Core Image effects to slow down. In order to enable it you have to install the XCode tools and then run Quartz Debug. And it resets back to "disabled" when you reboot. So even if you have a new fancy video card, your CPU is still doing the work.
A future release (10.4.1? 10.4.2?) will probably enable Q2DEx once they get it ready for prime time. I think this is just one sign that Tiger was rushed out the door; they couldn't get this piece working just right yet, so they turned it off.
For those of us with Mac Minis and video cards that don't support Quartz 2D Extreme or Core Image, the option to enable it is greyed out anyway. The GUI does run noticeably faster due to the optimizations in regular Quartz Extreme.
Regarding the improvements in Quartz Extreme... it's definitely been optimized, so the GUI runs faster in Tiger than Panther, even on older Macs. However the work is still done on the CPU rather than the GPU.
The GPU-based rendering is something additional, called Quartz 2D Extreme. That (in theory) will dramatically improve performance because it offloads just about everything to the GPU-- and this is where you need one of the video cards that supports it.
The thing to note is that Quartz 2D Extreme is turned off by default in Tiger. Apple left it disabled because it still has issues-- for example, enabling it causes Core Image effects to slow down. In order to enable it you have to install the XCode tools and then run Quartz Debug. And it resets back to "disabled" when you reboot. So even if you have a new fancy video card, your CPU is still doing the work.
A future release (10.4.1? 10.4.2?) will probably enable Q2DEx once they get it ready for prime time. I think this is just one sign that Tiger was rushed out the door; they couldn't get this piece working just right yet, so they turned it off.
For those of us with Mac Minis and video cards that don't support Quartz 2D Extreme or Core Image, the option to enable it is greyed out anyway. The GUI does run noticeably faster due to the optimizations in regular Quartz Extreme.