I know there are some crossover posts here that are not exactly what the OP was about, so something to keep in mind:
Those of you on Nvidia cards, might need to look into going back to an older driver from August or earlier… This may resolve the issue for now, till Blizzard and Nvidia can figure out what broke between the patch and the driver.
Nvidia put out a new patch today, but it does not fix this issue.
Go here for the advanced tool to download a driver:
https://www.nvidia.com/Download/Find.aspx?lang=en-us
Make sure to use the DCH versions. You want the ones from August. Either August 22nd, or August 8th. Game Ready versions only, not Studio.
Once you have downloaded that, then you need to get this tool to fully remove the current driver:
https://www.guru3d.com/download/display-driver-uninstaller-download/
This tool will uninstall the current driver completely. Then run the installer you downloaded above for the older driver and you should be good to go.
This has been fixing the problem for now till a better solution is figured out by Blizzard and/or Nvidia.
This primarily helps those with slow responsiveness with menus, freezing, etc. Can’t hurt to try it and you can always re-update to a later version if you want.