Trowbee, I think you got that because your monitor's refresh rate was set to 75 hz. Anyways, I got 59 - 60 fps with a monitor refresh rate of 60 (It's better than all the other different refresh rates, because it is the only one that runs smoothly and doesn't slow down as much)
My specs:
Intel Pentium 4 Processor (No HyperThreading): 2.4 ghz
GeForce FX 5600 AGP (Running on a motherboard that can't handle AGP 8x, only 4x and 2x)
512 MB Ram
I don't see what would make any computer slow down.
Everything is basically low poly.
HP Pavilion | Intel Pentium 4 CPU 2.40 GHz
512 MB Ram | NVIDIA GeForceFX 5600 AGP, with 256 MB Ram