Peg2 G3 is fine.
MorphOS 2 runs pretty fast on it.
But you will need 256 RAM or more to be able to enjoy it to the max.
OS 4.1 is really fast on Peg2 but I only have seen it on G4 machine -mine-.
A friend runs it on G3 and says it is fast.
In general benchmarks say that in general OS4 runs faster (!) than Samantha on Peg.