There are some that may never really be emulated full speed with mame.
Both AMD and Intel plan on using multi processor cores in the next few years. This will help all systems.... but emulation. You will get a few % increase because you can dedicate a single processor to the emulator and all other system process on the other.. But currently it would take more time to sync the memory between the cores then it will be accessing multiple processors... And since no computer can handle it.... Don't expect to see it.
IE, not only are you waiting... but your waiting a LONG time... If not waiting for a mame core rewrite.