I played through the whole game this evening using RetroArch SNES9x with Super FX overclocking. Enjoyed it!
Master becomes a whole lot easier when you use the triggers to turn instead of the d-pad. It enables 90-degree turns with little error, for example. It makes turning much more predictable.
Interestingly, I played Novice at 150% Super FX overclock. But with Expert I had to increase it to 200%, and Master up to 250%. The frame rate gets worse as you go through the game due to the increasingly complicated track and level design, as you say.