Amazing comparison. OS4.1 seems to be under-optimized. 
I would expect it on the Pegasos II, to be honest. It seems as if driver level stuff needs a bit of work yet. Look at the USB as a prime example there, It seems as if 4.1 doesn't utilise the USB2 capability of the machine. As hardware goes, the Pegasos II is MorphOS's "home turf", so you can expect it to be pretty well tuned by now.
I wonder how many Pegasos II users actually have both OS?