I use No-frills CPU control from the Google Play store. It is free and with the overclock kernel Skelton made it allows you to set max to 1.608 GHz and min to 312 MHz. With the ondemand/deadline settings my g5a seems to have good battery life (>4 hours) and plays most of my emulators very well. The only emulator I have trouble getting great performance out of is PPSSPP, but I don't really know very much about the settings yet. Drastic DS, Nesoid, Gensoid, N64oid, and epsxe all seem to run well with these CPU settings.