Here's a post with some tips on how to eek the best performance out of your Pi Zero.

Here's a post with my and some other peoples experiences with emulation on the Zero.

FYI, many people say to overclock. I've tried literally DOZENS of overclock settings (some extremely mundane), on multiple Zero's - and every single one makes the Zero freeze after around 20 minutes or so (sometimes way sooner, sometimes a little longer), so I wouldn't recommend overclocking.