A PPPPPPPPPPPPPPPPPPPscriptum:
When I programmed for 65xx and 68xxx CPUs on Basic + Assembler I did
count process cycles for the op codes. Do you know exactly what the
result is, after you compiled your C code?
Don't believe me, but ask some classic musicians to do some MIDI
recordings using Linux + external equipment (internal Linux MIDI is ok)
and then ask them, if they are fine with the result.