TLDR : They way I fix it by using High Res Assets. (~50GB extra download).
you can access this by going to Bnet Launcher > Diablo IV > press gear icon beside the Play button > Modify Install > Game Content - Modify Install > Check the “High-Resolution Assets” > Confirm > Update.
but keep your texture quality at Medium if you play on 1080p after install.
-OR- try to use VPN if you have one.
What I experienced before : Screen Lock, Lag when opening Map, Inventory, NPC, Shutters, Rubber-banding, High CPU usage
Check on DTMAce post below for explanation :3
If you seems to have network issue after you download the Hi rez package, try to disable cross network on the Option.
Hopefully they fix the based game assets … I want mi 50GB back :<
EDIT : The removing and redownloading wont help. Because the problem lies on the files that stored in the Blizzard server when u install the game. (mi hipothesis)`
EDIT 2 : since it probably just server issue. So people also reported to be able to get around this problem with using VPN
EDIT 3 : trim the post to make it short
Bonus : Also check your battery mode on your GPU it might be on “maximum performance” – happened on me.