I would like to know how many frames you are getting in the Simple.ppl and Simple2.ppl demos.
Make sure you keep the Simple2.ppl at it's default location (not moving the screen around with the arrows.)
My system:
Asus A620 @ 400 Mhz
Simple.ppl = 130 - 144 FPS
Simple2.ppl = 61 - 64 FPS
Regards,
Kornalius