[kjs3]

Well, that's kinda where 8051s get weird (not by a stretch the only way it's weird). 8051 performance is more '2 dimensional' in the sense it relies on clock speed as well as instructions-per-tick.

The 'classic' 8051 is (over simplifying) a 12-clock ticks per instruction processor. So you pretty quick had the second source providers introducing 6-clock and eventually 1-clock per instruction variants, with commiserate increases in speed. And then they jacked the clock speed.

So now you have '100 MIPS' 8051s, running at high clock speeds and 1-cycle per instruction.