> I wonder if custom compiling MAME with -march=haswell would make any performance > difference (running on Haswell CPUs, obviously). > > Or maybe -march=native instead if compiling on the target CPU itself.
You can get some gains (particularly with Voodoo emulation) with ARCHOPTS="-msse4.2 -mpopcnt -fomit-frame-pointer"
Avoid -march, it causes more problems than it's worth.