To make a fair comparison, I had to do the test standing in the same spot. If I turn just a little bit to the left or right, I pick up or lose dynamic lights, transparency, geometry, etc. so my frame rate fluctuates quite a bit if I test it looking at different things, and I wanted to rule that out.

As an example, dynamic lights normally don't affect my frame rate, but if I move so that a dynamic light is filling my frame, it slows performance significantly. But generally, geometry is the bottleneck. That's why I was quite surprised that compiling with higher precision didn't help more.

r00tsh3ll:
The thing I need to keep in mind about video cards is fairly different from the concerns I generally see posted on this forum because I am selling to the average consumer, not the hardcore gamer. NVidia and ATI are both outsold by Intel--especially in the average PC market. They're not nearly as sexy, but they're more prevalent.

Also, I have to worry about cards made 3 to 5 years ago, rather than what's going on in the market lately. I mean, if a consumer has an ATI or NVidia from the last few years, I have no worries that they'll be able to run the game at a perfectly acceptable rate.

I WOULD like to offer some nice eye-candy for folks whose video cards can handle materials and shaders. However, my estimate is that very few video cards in the general populace can handle these effects yet. JCL recently quoted a survey that reports the average PC these days is a 2 GHz with a GeForce or Radeon--but that's a very misleading survey--at least for the average buyer of a 3DGS-made game. This survey was taken by Valve for Half-Life 2, and basically was directed at hard-core gamers. I certainly believe that the average hard-core gamer has blazing PC specs, but the average PC is going to generally have about 1/4 to 1/2 that power, so unless I decide to compete head-to-head with Half-Life 2, I need to make sure my game will run well on the minimum specs for 3DGS: about a 500 MHz with a decent video card. And as far as I can tell, "decent" means that it was a cheap card from 3 years ago or a very nice card from 5 years ago. Anything other than that can't seem to run anything decent and they're lost to me.

However, I'm just estimating on a lot of this stuff, so I love the insights that you folks are sharing about what the real limitations are of older cards.