The below is a blizzard CSA on another thread. It is being fixed, but they don’t seem to know Mac can’t use Directx, which is sad.
"So I have checked and it does seem like we do have an issue with MACs currently that is being investigated and fixed, it’s causing FPS drops, crashes and other such problems for people.
It seems to be an issue with some of the changes to WoW Settings in the patch and there is a possible workaround I have seen that changing to DirectX11 may work. We have an open topic on this here ."
Note, this does not stop the crashes. but you will have a clear picture before it crashes and restarts you Mac.