By enabling the latency reduction feature in Recalbox menu, most emulators supporting retroarch run-ahead feature do actually have that enabled, with 1 frame of latency reduction, alongside with the auto frame-delay option enabled.

This is not true for fbneo though, the only arcade core supporting retroarch latency-killing features.

Why is it so?
Has it been omitted intentionally? If so, why is it?

Secondarily, I've noticed that by default the run-ahead option "use second instance" is not enabled.
I've read it is recommended so, please, why has it been disabled there? Using RGB dual for what it's worth it.

Many thanks for any help!

Yup, thanks for your reply. Unfortunately what you suggest is actually what I hoped to avoid: I have no extra storage for those ROMs other than the SD where they are right now.

Also I made some bootcmd customizations, and other tunings as well, so I hoped to be able not to do everything manually again.

So the only alternatives a far as I have understood are buying a new SD card and moving all the settings or sticking with Rpi3, right?

Hello everyone. I couldn't find this in the forum nor in the documentation, hope I didn't miss it.

I was happily using recalbox on a raspberry pi 3B+.
I now got a Pi4 and discovered that the very same SD card won't work on it.

I then realized that for Pi4 there is a separate image.

How can I upgrade the image so that it can run on a raspberry pi 4 without needing to reinstall everything (and copy roms and all my customizations and the like)?

Thanks so much.