I just installed Catalina and ever since I am expereinceing longer loading screens, slow loading Ui elements (maps, inventory) and slow loading mounts (the mount cast bar is finished, I dont see the mount and I cant move and a few seconds later I skiped ahead)
2019 iMac, 10.15.3 Radeon Pro 580
It’s a combination of Blizzards filesystem, APFS and your spinning hard drive.
The best thing you can do is delete WoW and reinstall. That’ll help get things loading faster. Leave it downloading overnight if you need to.
Just out of curiosity, why dont I see similar issues with classic? Interface items like maps and bags are loading as snappy as always in classic, upgrading to Catalina didnt seem to have any effect?
I have same issue, I have resintalled twice already, and still nothing solved. 
Same problem here. Loading screen isn’t bad, it’s ok. The main issue is everything from NPCs to map elements take about 40-60sec to load, while my character is frozen. Any fix to this, Blizzard?
If your hard drive isn’t an SSD drive, you’re kind of screwed under Catalina/Mojave. Both of those basically use the APFS file system which was written for SSD drives.
If it’s not an SSD drive, you could downgrade your OS to one that still allows you to format your drive in HFS or run the game under bootcamp, thereby eliminating APFS from the equation. Maybe even install WoW on an external drive if you have the throughput to run a game externally.
Keep in mind that WoW uses a CASC filesystem, which in and of itself, also runs better on an SSD drive. So damned if you do and damned if you don’t scenario.
Don’t bother deleting WoW and reinstalling on a drive formatted with APFS. You will see ZERO improvement. Personal experience speaking here.
[Edited by Blizzard] This thread has been inactive for some time. Please be mindful of resurrecting older threads. A new or more recent thread can be created to continue the discussion. Locking this thread.