Snes9x Emulator Controller Latency

The list of possible sources of lag, in decreasing probability order:

• HDTV. You are probably using one with your Mac mini. Put it into game mode if possible. Disable fancy options named "intelligent frame creation" or something like that. Connect a PC monitor instead, or, even better, CRT, if you still can find one. The amount of lag varies wildly between HDTV models, from negligible to unplayable. Home theatre video processors also add lag.
• Emulator & video card configuration if the emulator is using 3D acceleration features for some reason. Try using simpler video configuration, disable filters etc. Try different emulators. They do add lag, some less, some more.
• wireless controllers (some have virtually no lag, some add a lot)
• wired controllers and keyboard. Unless something went really really wrong, the amount of lag they add is tiny.
• can't say anything about the operating system. While I'm writing this from a mac I only use emulators on windows and on portable devices.

I also noticed a lot of latency with a bluetooth SNES controller and Snes9x 1.60. It was fixed by checking this setting:

Video -> Display Configuration -> Reduce Input Lag

If that doesn't work you can also try turning off graphics scalers and other filters.