MBP 2.0ghz core-duo, 1gb ram
1 min 5 sec in Photoshop CS2
35 sec in CS3
The CPU isn't taxed at 100% through all of it. It sits at 100% for a second or two, slows to ~60% for about a second, and then jumps back to 100% for a few secs. I can only assume that there isn't enough ram bandwidth.
Also, after being opened once, and quitted (ie. CMD + Q), CS3 reopens in about 3 seconds on my MBP, including bouncing time. Even after websurfing for an hour with CS3 closed the files still stick in memory and CS3 opens nearly instantly. This is really going to help for all those times I close the program instead of the window..