G3 to G4

Under OS9, there isn't much of a speed difference, but under OS X, there is a significant difference because of g4 optimizations and altivec optimizatios in OS X.

Figure on around 30-50% on a a Mhz for Mhz basis in OS X.

i didnt even think there was that much difference.....

Under OS9, there isn't much of a speed difference, but under OS X, there is a significant difference because of g4 optimizations and altivec optimizatios in OS X.

Figure on around 30-50% on a a Mhz for Mhz basis in OS X.

...for applications optimized to take advantage of Altivec, yes, but other than that, there won't be any significant increase in performance in OS X, either.

From everything I've been made to understand, the only major difference between the G3 and the G4 was Altivec capability.

For a list of apps optimized to make the most of Altivec optimization on a G4, click here, (this is by no means a complete list, but should be about 98% accurate). If you are not using any of these apps, then you won't see any significant speed difference.

...for applications optimized to take advantage of Altivec, yes, but other than that, there won't be any significant increase in performance in OS X, either...(snip)

...If you are not using any of these apps, then you won't see any significant speed difference.

I did a straight-across G3->G4 swap in my B&W G3 (400Mhz for both CPUs), and I will say *subjectively* OS X "feels" significantly faster with the G4. The various little bits of eye candy in the UI, like the window move/scale operations, bouncing icons, drop shadows, etc, etc, all seem to benefit from G4 optimizations. It's not a make or break thing, mind you, but it's definately there.

That said, I wouldn't spend any significant money on an upgrade for a G3 Mac. All the "upgradable" ones are officially "vintage" now, so expect the axe to fall on their necks during the next OS X upgrade cycle.

http://docs.info.apple.com/article.html?artnum=112142

--Peace