Dear PASCAL DMCHRETIEN
Thank you for posting to Microsoft Community
Based on your description, I understand that you are experiencing high CPU usage while typing emails in Outlook 2016.
I understand your frustration, but the issue has not been successfully resolved in Outlook 2016 even though you have troubleshot add-ons, graphics acceleration, and deactivated spell checking options, and the issue is primarily occurring on Windows 11, so I would recommend that you contact Microsoft Online Support directly, where you can communicate with them about the issue you are experiencing via chat, and ask them to remotely, if necessary! Chat specialists will answer your questions immediately. The chat window is one-on-one and the chat specialists will answer your questions immediately and deal with them more efficiently!
you can click on the link below to log into your personal Microsoft account and chat directly with chat support.
- Open this link Contact Us - Microsoft Support
- Select Office. At the bottom of the page. Select the Contact Support option.
- Select Microsoft 365 and Office.
- In Categories, you can select Technical Support and confirm it.
- Then select Chat with a support agent in a web browser.
TIPS: Please contact us during local working hours on weekdays, CHAT does not work 24 hours a day.
Wish you all the best and have a nice day!
Linda.W-MSFT | Microsoft Community Support Specialist