Actually the mame compatibility is very bad. We have version 0.36b or something similiar and now mame is at version 0.145.
This is why we need mame, FBA, cps2, gngeo, neogeo cd and so on. Cause the mame compatibility is really really bad. C64 is just horrible, I just can't understand that it has a horrible looking interface and it lags when we have many emulators like pcsx rearmed and drPocketSnes that emulate really more powerful machines than the c64 but they do not lag in a lot of games....
I will contact the dev anyway. Let's wait...
EDIT: Message sent!