@marcdk Dude, I know you can probably guess by yourself that:

we are not Retroarch pros some settings could have been written AFTER recalbox was started we can't keep an eye on every Retroarch commit + every libretro core commit + every emulator commit + every buildroot commit just regarding dispmanx, I'm the one who added it on 4.1 we terribly lack time and/or contributors to do this ground work and yes, we also aim for the "most compatible" configuration in terms of emulation but also arch (pi, odroids anx both x86 share the same RA configuration file)

We're really open to get feedback from users if they are willing to improve anything. But just read our commit log, just check by yourself : hardly any one does.

Now a little earlier in the conversation you asked

So please tell me how to significantly reduce the input lag on recalbox with a raspberry pi. I will measure it and extend the article right away.

@joinski gave you some leads, so go ahead and try it by yourself, measure it, write blog articles if it's your hobby. We both know it will never reach the latency of a modern computer or a dedicated box. But it can be slightly improved, maybe to a point where you can feel "more comfortable" when playing, without ever reaching what a PC can do. Regarding PC, i also remember that some libretro forum member made some measure and sad a windows PC was around 7 FPS of input lag, linux was 1 FPS above.

The input lag investigation says it all, is very complete regarding tests, the way they did it etc ...

Retropie gives a few tricks, despite i'm sceptical about the video max swap chain, i was told to put it to 2 or even 1 by libretro members.