ok, are you sure its the mac and not the internet? have you tried unplugging the router, change out all the old cords for new ones?
What is the upload/ download for the internet?
also, is your graphics card being used?
I have a windows computer but ever since a patch the game had been having issues using the graphics card. Turns out the settings were pointing to a wow.exe location that was no longer valid.
Wow is now located in the retail folder.
maybe also check which directX option you are using the added a legacy version and the normal one.
depending on how old your computer is it might just not meet the requirements for the direct X option you are currently using.
*note: leaving as is but mac does not appear to have a DirectX option so idk what Graphics API options you might have but i assume the was a similar change and they appear to have made Changes to the API to allow for multi core processors to use multiple cores among other things.
also you might have better luck looking in the Mac support form.
seems the issue has been tracked down to a driver issue related to your graphics card so make sure your drivers are up to date. other than that