GameCast - your setup seems to be over powered that's why you don't see any diff with or without nvidia drivers 🙂
during your test have you activate FPS to be sure you are not running under fps sometime ?
the most consumming emulator so far is PS2 or 3DS ..
poke overall most user won't see the diff if they have good any configuration but having the most of an hardware help quite a lot and if ps3 emu or wii u emu are going to batocera i'm sure that this will make a diff