I am experience soomething similar. The lagging start abou 10 minutes into the game. If i click the mouse more that 4 or 5 times, I get a mesage saying the app has stop reponding, do you want to wait. AT that time the game will never resume. You just have stop.
During this time the music continues toplay but i is ‘scratchy’ or ‘staticy’. Also if you make threw the game and exit at the main, the muisic continues for xeveral seconds after the AOR window closes.
The stuttering and scratchy sound has been occuring for several months off and on. Sometimes an update fixes the bug but then a future update reinstates it. I checked my vertual memory snf it is not fcompletely used.