For those who do not have, or are not inclined to work with 
CodeWarrior, Apple Computer distributes free (as in beer) a high-end, 
high-quality professional development system including Motorola's 
highly optimizing MrC compiler.  My recent experience has been that a 
high quality Squeak VM can be built with MPW, which VM in some ways 
outperforms the standard release.

I built a changefile and FAQ laying out how to build the Squeak VM 
and Squeak3D plugin for PowerPC with Apple's MPW development System. 
All are available at:

	<http://www.gate.net/~werdna/SqueakMPW.html>

Generally, I found straight-line bytecode interpretation to be 
slightly slower than under CodeWarrior, but the sends/sec 
substantially better.  And for compute-intensive code, like the 
Balloon3D stuff, it seems to generate slightly faster code with 
slightly faster framerates on my iMac.

I'd be interested in the experience others have had on other MacOS machines.