High CPU usage when typing a message in Outlook

Hi all,

I posted a Known Issue article to formally track it, CPU spikes when typing in classic Outlook for Windows - Microsoft Support. The Outlook Team is currently investigating. I'll post back when I know more.

@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.

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?

Dear Gabriel,

I did some testing today and although subjective I believe I see the CPU spike more starting with build 17726.20126.

To see if you can confirm this, revert to the build below and test. The build in the steps below is for Current Channel. If you are on a different channel let me know what it is, and I will find the appropriate build. Builds available to revert are on this page, Update history for Microsoft 365 Apps (listed by date) - Office release notes | Microsoft Learn. The revert steps should take about five or so minutes and you will need to close the Office apps.

Steps to revert Office to Current Channel build 17628.20110:

1. Open a Command Prompt in Administrator context.
2. Type or paste the two commands into the Command Prompt window and press Enter after each:

cd %programfiles%\Common Files\Microsoft Shared\ClickToRun

officec2rclient.exe /update user updatetoversion=16.0.17628.20110

Alternate command to those above:

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

On my system, switching off text predictions and checking spelling and grammar, which I had already tried during the months before, did not solve the problem, but only changed the CPU usage slightly.

I had also some months ago already tried rollbacks of MS 365 incl. Outlook to versions 2410, 2409, 2408 and 2406, with no change concerning this issue.

You now mention build 17726.20126 (version 2406) as starting point of the issue, but build 17628.20110 (version 2405) should be OK. By the way, here's the version history again: https://learn.microsoft.com/de-de/officeupdates/update-history-microsoft365-apps-by-date?redirectSourcePath=%252fen-us%252farticle%252fae942449-1fca-4484-898b-a933ea23def7

And here's the offical rollback how-to: https://support.microsoft.com/en-us/topic/how-to-revert-to-an-earlier-version-of-office-2bd5c457-a917-d57e-35a1-f709e3dda841

So I will try the rollback to 2405 soon and let you know. If it should work, that would be at least a work-around - but the bug must nevertheless be fixed by Microsoft, because we shouldn't stay at an old version too long.

Hi Gabriel, I have the same CPU usage issue running v16.0.18324.20240. I've tried turning off "Check spelling as you type", "Mark grammar errors as you type", and "Check Grammar with spelling" but it hasn't worked. Any other suggestions please?