I've owned TG-16 stuff for ages, altho I haven't played my real system in a long time.
However, I think 133Mhz/30fps is actually a bit slower than the real thing in many games. 133Mhz/20fps often seems too fast however. TG-16 games tended to be pretty frenetic.
Better be careful running above 133Mhz - even if your GP32 appears to work OK at that speed, it could destroy your display hardware over time.