AGP-Speed Benchmark Results - Quake 3 Arena
Things change when testing with Q3A at the 'Normal'-setting, which runs at only 640x480, has only 16-bit color, low texture-detail and less polygons. Technically even AGP1x is still sufficient, in case of i840 you can not even see any difference between the different AGP-speeds at all.
In the 'High Quality' settings the game is a lot more detailed and at least some effect of the AGP-speed kicks in. If 4 fps are important to you, you might wonder why AMD claims that there's virtually no difference between AGP1x and AGP2x on Irongate, but I do admit that less than 4% are not exactly a huge difference.
At 1024x768 GeForce's fill rate or local memory bandwidth is starting to even the results out, the results are not differing a whole lot at all.