Boe

Hi there! I've been using open source firmware and enjoyed it alot.
However it seem that it uses more processing power and thus projects that sounded ok on og firmware now have a bunch of notes just abruptly stop playing. I thried things like not using unison on synths, less delay, less reverb etc. Also when I set up the priority of a track with alot of voice stealing to HIGH then this track sounds fine but every other track is just messed up. I tried to return to og firmware but when loading this particular project it couldn't open and showed the FIRM error on numerical screen. I assume it tries to say that this project is not compatible with this og firmware, but i didnt really use any features of nightly firm on this prticular song. So i downloaded nightly firmware again, installed it. And now this project has eve more voice stealing for some reason
I cant really figure out what's happening and how to fix it. Can someone point me in the right direction?
Maybe there is way to turn of features of new firmware so that it can open on older one?