barn wrote:But now that I think about it – isn't it that the aqua surface uses 3D-rendering for its objects?
Aqua uses transparencies in it's display of graphics which is provided by the display rendering engine (Quartz) which is based on the PDF file format. Mac OS X is the first system to use PDF as a display format (previous systems used either Postscript or Pict for the display format).
What you'll find is that at this point the rendering of elements on the screen is not actually slowing the system down at all anymore. On the other hand some key graphics elements of the GUI are designed to display an effect over a certain period of time... no matter how fast or slow your system is. The fastest G5 should display something like a dialog sheet lowering into place at the same rate as a first generation G4. Most people who expect all those animations to be tied to the processor speed are usually disappointed when all those effects are pretty much unchanged. The animations in the GUI are like quicktime movies or mp3s. Your favorite song shouldn't play any faster on a fast system, it should take as long as it takes. It is the same thing here.
On a side note, Apple has changed the time needed for animations in each successive version of Mac OS X since the Developer Previews. The most noticeable change came in the jump from 10.1 to 10.2.
Also, removing Aqua is removing the application environment for most Mac applications. I, personally, have found that apps not running at all seem slower than apps that can run... but that is just me.