High CPU usage when typing a message in Outlook

@Matt,

Thank you for sharing the case number. If I need to have an escalation engineer submit the hotfix request, I will use your case. Since I repro the issue, I have already taken the traces needed to escalate and have shared those to an escalation engineer to investigate. I'll post back when I get a little further along and figure out next steps to get this fixed.

@dark-rider,

Any subscription of Office should be able to be run on any of the major channels. The easiest way to switch channels is by using the registry key method I shared above. It's been a while since I used it, so I want to double check again on my test VMs before sharing the specific steps. I recall too that if you use that registry key to switch to Semi Annual, you will need to click File, Office Account, Update Options, Update Now after setting the reg key for Office to initiate the change. I want to make sure the steps are thorough, and I note any considerations. For now, if anyone needs relief the best option is to revert to the build before the issue started.

Steps to revert Office to Current Channel build 17628.20110:

1. Open a Command Prompt in Administrator context.
2. Type or paste this command into the Command Prompt window and press Enter:

"%programfiles%\Common Files\Microsoft Shared\ClickToRun\officec2rclient.exe" /update user updatetoversion=16.0.17628.20110

3. To prevent Office from automatically updating back to the latest build click File, Office Account, Update Options, Disable Updates.
4. Put a reminder on your calendar to check back on this form thread on April 15th to check status.

My ticket number was #2412110040013308. It seems MS closed my ticket and isn't responding to emails when I reply in that conversation. I may have worn out my welcome in that thread.

Dear Gabriel,

Matth22 (with his posting on the bottom of page 3 of this thread) reported that he was intensively working with Microsoft on this issue. So he should have a ticket number, could you ask him and if possible escalete it for a hotfix request?

Concerning SemiAnnual Channel: Isn't this only possible for Enterprise customers? When I understand it right, this channel dispenses with functional upgrades, but just offers security fixes, right? So in comparison to the rollback to 2405, you would get the latest security fixes further on. There seem to be three different SemiAnnual versions (2308, 2402 and 2408). Which one to choose and how? 2308 and 2402 should be OK, but 2408 is newer than 2405 and should include the bug again? Isn't the SemiAnnual channel upgraded every 6 months, so that this would only fix the problem temporarily until the next upgrade comes?

@dark-rider,

Was your support case opened through the M365 Admin Portal? Does it have a number such as 2503060010001954? If it's a commercial case, I would like to see about getting this routed to classic Outlook support and get this escalated for a hotfix request. If you still have the case number, please share it.

Also, there is another workaround that should work for this issue. You can switch Office channels to Semi Annual channel. The reason I suggest this is it will ensure you are on the latest build, so you have all the security updates. Also, this channel is the slowest to get feature changes and for example does not have Text Predictions. I tested this channel, and it does not spike CPU when typing for me.

I will post some steps tomorrow to switch channels to Semi Annual channel. There is a way to do this with one registry key but I want to test it to double check it works as expected, Use a registry command to install Microsoft 365 Insider on Windows devices - Microsoft 365 Insider | Microsoft Learn. The channel to use with the registry key is SemiAnnual.