/me looks at his *almost* complete rom list, and didn't found even a game which matches with mp1 a little bit. Maybe Monopoly, but that's my opinion.
Anyway: Mupen doesn't run much games at a nice speed because it hasn't got a dynarec or another special system (like Corn, and the original Ultrahle), but it's using interpreter mode. Mupen has the fastest interpreter of all emulators but it's still pretty slow. This causes a lot of sound-clicks (even at full speed) and slowdowns. Hacktarux (= author of Mupen) is busy with adding a nice dynarec to his emulator, so standby.