Quartz ain't a factor
Quartz is PDF display and OpenGL and is not even used by any of the major applications like Illustrator, Photoshop, Freehand, Flash MX, Painter 7, AfterEffects, Lightwave...
The only application that I have that uses Quartz is OmniWeb and MS Office, and Office's use of it is limited. Quartz is slow, though. OmniWeb is slower than IE because it uses Quartz and IE doesn't. But that's why OmniWeb looks beautiful compared to IE. But both of them are slow.
Photoshop uses its own graphic engine.
The reason Razor thinks Photoshop for OS X is slow is because OS X's GUI is slow - period. It isn't hooked into the GPUs of our graphics cards like OS 9 or Windows is. Turn off your ATI or nVidia extensions in OS 9 and see how slow the Finder gets. That's how OS X is all the time. As soon as Apple hooks OS X up to the GPUs of the graphics cards, the Aqua UI will be much faster. But I've noticed that all of the functions in Photoshop, like filters, mode changes, etc., are all very fast.
Also consider that a lot of these developers are just learning OS X development. Some are better than others. For example, Flash MX is down right snappy in OS X, but Freehand is not at all.
Razor, Flash doesn't display everything as a vector. How do you convert a bitmap into a vector?
Where can you buy a dual Athlon? I priced the parts for a dual Athlon and it came out to $2,500 with Win XP Pro. I priced a dual Pentium 4 Xeon and it came out to over $4,000. I don't think the $2,799 price of the dual G4 1 Ghz is too high at all.