ZINC may run it better on your system. I know that may not be the purpose here if you only want MAME to be able to run it better. I recently built a Core2DUO system and finally the looping sound is gone, but I play the sequels more often than the original. (on Dreamcast and playstation.) Have you tried turning off AUTO frame skip, and manually setting it to half frames or anything? ZINC had run the game better(well, as in more playable) on my previous system than MAME. That system was a socket 754 newark. A C2D just for this game is more expensive than the added price of a used Playstation + Dreamcast + all three games combined!
I know, I know that's just not the point, is it? I have been there.