What is "full speed", because full speed refers to whether or not it plays in real time with the original game. MOST people use it to mean whether or not it has to skip frames to do so. You won't have a hard time finding fullspeed w/fs0 (for a majority of games) emulators for Gameboy/Gameboy Color, NES, SMS, Genesis, and other old platforms. You'll have a harder time for SNES, GBA, Amiga, and PC-Engine (for now), depending on how high you can overclock. Forget about Jaguar or PS1.