I tried it on .60. Worked at 100% in that. But only getting 55% of so in the higher up versions.
UPDATE: I changed MAME to use Direct 3D for Tempest. It's now working at 100%
Guess my 1800+ (1.5 ghz or so) is too slow to run those versions normally? Don't know why my PC is listing that machine at 1.15 ghz though. (ANOTHER UPDATE: I'm a bit of a novice here but it appears I must have PC100 RAM and my machine won't run the processor at a frequency of 133 if the RAM is at 100).
Also, I had to stop using bezel/overlays/etc. for Asteroids. No matter what I did with it, I couldn't get it to run over 75% using those. I got rid of 'em and it runs at 100%.