In an AMD Athlon 2200+ with an GeForce 4 onboard (very bad,specially with Opnel GL aplications),no slow downs in Zelda OoT,MM,Mario Golf,etc.All with frame buffer on.A little slow down and a "fliker" in Banjo-Tooie.
Ah,yes,the IDLE slow down a lot,but it´s still at 60 FPS