Using Classic Outlook on Windows for personal email, calendar, and contact management
The main issue for now is the limit to how many actionable messages can be opened before you need to close some to be able to open others. The short answer is that the limit is 10 for all channels except SAC which is 5 and it will go to 10 in July's major update, Error when opening Actionable Messages - Microsoft Support.
The next change that will make things better is currently targeted in the May timeframe (no ETA yet on prod release though). This change should help address the WebView cache & reuse that is probably being helped by the WebView repair. There is also investigation to see if the current AM limits of 10 can be increased.