@lesk Deopending on the emulator and version I think, as it is a relative recent feature. You may need to update RetroPie. There are entries in the emulator menu for this feature: SETTINGS > LATENCY. I looked up in Snes9x 1.56.2, Nestopia 1.50-WIP and MAME 2003 (0.78).
The Raspberry Pi 3 is too weak and it would be extremly slow and painful (as far as I know). Which emulator and version do you want use this for? Try the "lr-" versions.