Very slow saves & slow view/hide instruments

I'm on MuseScore 4.5.2, Mac Sonoma 14.6.1. I'm working on a score that's about 125 bars and 25 instruments. I'm on a decent machine -2.6 GHZ 6-core Intel core i7, 32 GB RAM and lots of room on the HD.

Problems:
1. Saves are very slow, estimated 30-60 seconds
2. Earlier every operation triggered the multicolored wheel; however a restart seems to have cured that
3. When I click on the eye to open/close an instrument display in a part, that is also very slow.
4. Two earlier versions had key errors for specific instruments. The first time my trumpet2 appeared in a different key than trumpet 1; it seemed to happen randomly. Cured by deleting trumpet2, re-adding it and pasting in the part from a slightly earlier version. Same thing happened a few versions later for flute. Neither of these instruments was changed - e.g. flute was always flute and never changed from a transposing instrument.

I don't know that #4 relates to the slowness but I'm including in the interest of thoroughness. #4 happened when my collaborator was working on it, rather than to me, so I can't detail the operations that happed immediately before. I have had this happen to me a while ago as well, but I haven't done any serious arranging for a year or more so I can't provide details or even version #'s.