Using New Outlook on Windows for personal email, calendar, and contact management
Everyone in my office has had a problem with the new Outlook: errors displaying new mail, excessive CPU usage and memory consumption (large percentages of these) - you all have problems and that's why you're here.
Uninstall the "new" outlook.
Then download the new one (it will say it's an "offfice download" but it's just Outlook:
https://go.microsoft.com/fwlink/?linkid=2276500&clcid=0x409&xcust=2-1-2469158-1-0-0&
For reference, I got the URL from this story: How to download the 'old' Outlook app if you hate the new one | PCWorld
FWIW, I also did do the regedit of the keys provided in the first few pages of this thread; I even created the path that it indicated should be there (as well as added the flag to the path that seemed to be there.)
Good luck!
Steve Powell