As an experiment, I uploaded some of my photos to work, and installed Lightroom Beta 3 on my Core Duo mac mini at work.
The difference in performance is.. well.. depressing. As Lightroom doesn’t use CoreGraphics, it’s particularly dependent on CPU power, and the Core Duo just kicks the crap out of the G4 that it’s not even funny.
On my roughly 6M per file Nikon D70 NEF’s, the re-rendering after adjustment is so fast, that it feels almost just like Aperture. Those Adobe guys really aren’t messing around when it comes to image processing algorithms.