While "code optimization" can account for some... these guys optimize as much as they can in the first couple of driver iterations. I was careful to say "likely" in that sentence too btw. (Can you tell I'm in the software business?)

I also mentioned that you couldn't get a speed increase like that unless the previous versions were screwed up pretty bad. Honestly, "code optimization" is normally geek-speak for re-designing to avoid the problems encountered in earlier versions. It's not really "optimization" all. When you see a big speed increase in a piece of software, they either fixed a bug that was crippling them, or they did some sort of re-design to build a faster product. Im' in the QA/QC side of the software business, so I've been through this before.
I guess a more accurate statement would be that speed improvements of the 50% range nVidia was touting won't come out of code optimizations alone. My fear was that lots of folks would believe what they were implying and mess up AH with buggy new drivers.
Here is a clip from the little press release nVidia sent out via email:
Detonator XP also includes:
Performance increases of up to 50% in Microsoft DirectX and SGI OpenGL
applications.
Although carefully worded it gives the impression of a huge speed increase. A false impression for all but GeForce 3 owners I might add. I want to make sure folks don't go slapping these new drivers in their nVidia cards and expecting a big improvement. Every time nVidia puts out a "faster" set of drivers, I spend a crapload of time helping people "fix" their machines by going back to the older ones. I'm just trying to save myself (and others) a bunch of extra work.

I learned this the hard way... just passing on the wisdom so you all don't have to learn it the same way.
