Well, if your Amd is a K6 or K6-2, your problem is the heavy use of math calculations that the emulator does. It runs on that CPUs but sometimes, especially when there's a lot of fog, the cpu can't keep up with the emu and heavy slowdowns occur. You can disable Software Advanced Blending, as I know vodoo 3 doesn't do that in hardware. But be warned you'll miss some special lighting effects