I'm updating from .78 to .88 with each rom set upgrade, mame windows command line program, and using clrmamepro for .88.
After playing with a couple things, I wanted to make sure it was actually WORKING before I set clrmamepro loose on the whole system (which takes a while) I loaded Dig dug. Took probably 10-20 seconds (before was 3-4 seconds)
Loaded Pengo and it took about 20-30 seconds (3-4 seconds before)
I could be WAY OFF on those times, but that's sure as hell what it felt like. I tried using the pentium pro optimize as well and that didn't help much (if any)
Using a P3 - 800mhz with around 512mb SDRAM - windows XP