Same problem (on imac, flicker, freeze, force quit, etc...). Very annoying. It improved a little bit when I set the game with "Draw fewer graphics" but the problem eventually came back. Are you playing on Steam ? If so, the solution is here: http://www.spiderwebsoftware.com/queenswish/support.html#MacIssues It just says to turn off Steam Overlay in the game setting (can be tricky to find). Problem solved. Except, it just happened once again since then so it's much, much better.