Yes, Star Fox, Stunt Race FX, Vortex, Dirt Trax FX, Dirt Racer, Winter Gold and Doom are not well emulated with or without the overclock setting with the snes9x next core, graphical glitches here and there and runs way faster if the FX cpu is set to a higher number, but at least are pretty playable (except Doom), imho for those titles it's better to disable it. The only game that benefits is Yoshi's Island, it helps with slowdowns the game has even with the original hardware.
Really? I don't remember glitches in Star Fox... But I admit that a lot of time has passed since I played that (and it was under 1.0.0.2), so I could be forgetting things.
It's a minimal glitch, but it's not present on the original hardware. Right after loading the Star Fox rom it's noticeable, despite that, there's no more graphical glitches and it's perfectly playable, just the FX cpu speed going between 5 - 6 fps faster (overclock disabled) versus 11 - 14 fps faster (overclock enabled) due to inaccurate emulation.