I stuck with the new build and it is slowly getting better but not at parity with old app. If you get hung up, I recommend you quit out of the application and log back in.
I am glad I am not the only one! PAINFULLY slow. Works for am minute when I exit and restart, then slows again. The old version was great! I want it back!
I am on 10.5.7 build 2171 public
Macbook Air Catalina 10.15.7
8GB Memory