I already did some power consumption optimization on the hardware side, but I don't think that you can really improve it on the software side. I tried to put the atmega into sleep mode between each frame, but it didn't worked very well. But the sleep mode could allow you to do games like tamagoshi, which require the console to stay on for long periods of time. I'll do an example game to explain all that
If you have any other suggestions, they're welcome !