@stefan.chirila @Morgan_Hardwood I have prepared a new version of the AppImage that, at least on my Ubuntu 16.04 system, runs practically as fast as the native 5.4 version installed from PPA. The link is here: https://github.com/Beep6581/RawTherapee/releases/download/nightly/RawTherapee-dev-5.4-266-ga84ce624.AppImage
Could you please check if you see a similar speed improvement? If yes, I will update the rest of the AppImage packages in the nightly release…
Thanks!