I haven’t posted here for a bit, but this started becoming a problem again for me after the 9.1 Patch. There are three locations I’m finding are creating constant updates - the .build.info file that is being set to wrong permissions (yes, again. Battle.net application gets fixed for some time, then it starts screwing up again). If you are using the Curseforge application from Overwolf, it is leaving a file .curseclient after it is run that has the wrong permissions, and triggers an update cycle as well. Finally, SOME updates will download with incorrect permissions, and that will trigger an update cycle as well. These three commands will fix the issues if run just before you start the Battle.net app:
chmod 777 "/Applications/World of Warcraft/.build.info"
chmod 777 "/Applications/World of Warcraft/_retail_/.curseclient"
find "/Applications/World of Warcraft/_retail_/Interface/AddOns" -type f -exec chmod 777 {} +
It would be better if you added them to your crontab and ran them every minute or so - directions in one of the posts above.
*Note: “Wrong permissions” means the file is not being set to permissions rwxrwxrwx (777). Any time the Battle.net application finds a file with “wrong” permissions, it triggers a full update sequence. Honestly, it would be better if Blizzard didn’t code the application to be so oddly picky, but this is the reality that we are dealing with right now.
I hope this is helpful to somebody. If it doesn’t work for you, sorry - just sharing what I’ve worked out on my own system, and what I know is working for me.