@phillip_benoit i just found a better one and used it and it worked instantly
Convertio.com

@mitu Thanks! I will try out to update and if it ruins everything, switch to a newer OS then.

For screen and mouse/analog rotate (book mode), see here for a workaround:

https://retropie.org.uk/forum/topic/29456/solved-nds-lr-desmume2015-rotate-also-mouse-axis-when-video-is-rotated

It relies on lr-desmume2015. It is a workaround as the book mode issue is neither implemented yet in the lr-desmume2015 nor in retroarch.

@Gokilz would you mind adding the rotate/book mode aspect to the subject on your initial post? This would make it easier to find this topic in future when searching for a similar issue as yours.

@StonedEdge hi there
can you share the arm64 binary to test?

An update - I did just try flashing a fresh card with nothing on it and it runs at full speed, so definitely not the Pi or RAM issue. I've uploaded a video here that hopefully shows what's going on. As you can see, the first percentage is 100%+ but the second one shows that not 100% of frames are being rendered, basically it's trying its hardest, but seems like things are being throttled back.