The low-end fill rate noted by Nvidia for their GeForce 256 is 480 M/pizels per second, barely 30% faster than the current reigning champion: the Voodoo 3 3500. Let's guess this truly is low ball, since the low end clock rate is a mere 120MHz. Guillemot has announced that their 3d Prophet, based on the same chip, will exceed this figure. Let's guess that Guillemot's board will top out at 150MHz and 600 M/pixels per second.
S3s Savage2000, on the other hand, boasts a fill rate 100% faster than the V3 3500. This raw difference in horsepower means that most 3d games would see a dramatic increase in speed apart from other factors, including improvements in CPU clock rate or onboard T&L.
The GeForce 256, on the other hand, boasts only a small improvement in fill rate along with an enormously powerful geometry processing unit (GPU.) But what this means is that the GeForce remains CPU limited. In order to utilize the massive power of the GPU, one needs a CPU of enormous horsepower. If the CPU cannot supply the pixel pushing horsepower, the only real benefit of the GeForce is the onboard T&L engine. This is great for games which support DX7, but the first simulations which do so won't be seen until Q1, 2000.