So long as it's running at 100% speed, the CPU(or memory) in the PC should not matter. Unless you're playing(god help you if you are) un-throttled that is.
I also seem to recall Otto taking longer to appear too but,
I've only been able to play it on MAME for many years so ??? I don't know...
I also seem to remember different machines starting at different levels/difficulty and the differently colored robots. In MAME there seems to only be 1 start option whereas in that yubeo his machine started with the white bots. Maybe there are still other undumped sets like what I remember floating around still.
Pessimist: Oh, this can't get any worse!
Optimist: Yes, it can!