Yes you are skipping frames. A faster CPU would definitely help you.
I didn't see a mention of what MAME version you are using, but generally an older version of MAME will also give you a performance boost.
I`m (or my buddy) is in the process of updating me to .127. Actually got a great price on a system I may order this weekend.
Intel Quad Q6600 2.4 Ghz
2 gigs 800 Mhz RAM
500 gig HD
256 ATI Radeon HD 3650
Will be running windows XP Pro
Perhaps overkill on the processor, but I can get this one for less than the price of a much lower performing e2180.
Only thing I am waffling on is....bump up to 3 gigs ram and stick with the 128 meg Radeon 2400 Pro, or get 2 gigs ram and get the above 3650.
I have read that mame benefits little from vid cards per se, but I`ve heard soso stuff about the 2400 pro card.
Any opinions from you mame vets would be appreciated..thanks.