I've had my PI 3 running for 93 days without ever shutting down. Emulation Station goes into a dimmed mode after a few minutes. What that does for power consumption, I don't know.

4 hours since last play system temperature is 42c. We have 21c in house. I don't have a heat sink, but I haven't attached the top lid either.

The nice thing about having it running 24x7 is that is gets out of dimmed mode nicely by pushing the X-button on the Xbox 360 controller and you're good to go...

Ok. Well, the SNES emulator should be able to run on a Pi3 easily enough. The best example I can give is Super Mario World Allstars + World. But generally, I imagine that the Pi3 should be able to run the SNES emulator without problems. I wonder if my RaspiATX card that controls the power is draining too much juice from the Pi3 thus reducing performance. Is that a possibility? I do have the switch that controls the pi from the board as an LED switch... ie it uses electricity as well.