Man kann in RetroArch wohl mit bestimmten Einstellungen noch ein bisschen was rausholen, siehe hier:
https://forums.libretro.com/t/an-input-lag-investigation/4407/583
"It’s interesting to see how the RetroPie setup reacts when we, one by one, apply the known input lag reducing settings. Combining them all, we can actually match the SNES Mini. However, this is slightly misleading, as there are a few drawbacks to using these settings. Using the Dispmanx video driver means you lose the ability to use shaders as well as the on screen text (for example when saving). The video_max_swapchain_images=2 setting is also very demanding and many SNES games will not run fullspeed with it enabled. You probably can use it together with the other input lag reducing settings for select 8-bit and 16-bit games, but it would be a bit cumbersome to setup and in that case I’d recommend switching to a more powerful platform (such as x86) instead. Choosing the middle ground of using the Dispmanx driver and disabling threaded video is certainly possible. This works perfectly for NES/SNES and will put you within a frame of the SNES Mini, given a fast enough input device."
Hier sind weiter unten noch weitere Settings aufgelistet, die den Input Lag reduzieren können (aber leider auch u.a. die Performance beeinträchtigen):
https://github.com/RetroPie/RetroPie-Setup/wiki/Input-Lag
Man sollte also wenn man SNES ohne Performance-Einbußen und mit möglichst geringem Input Lag zocken möchte entweder nen SNES Classic Mini (dort dann aber nur den offiziellen Canoe-Emulator) nehmen oder auf x86 Hardware wechseln.