High CPU usage when typing a message in Outlook

Hi all,

The CPU spike fix is now available in the Beta Channel (Version 2505 Build 18827.20006). If you are able to switch to the Beta Channel to test, please do. The Word Team will backport the fix to the other channels, and I will post back with those specifics once I get them and will update the Known Issue as well, CPU spikes when typing in classic Outlook for Windows - Microsoft Support.

Simplest steps to switch to the Beta Channel:

Use a registry key to Beta Channel. For more information, go to Use a registry command to install Microsoft 365 Insider on Windows device.

1. Open a Command Prompt window with Run as administrator for Administrator context.
2. Paste the command below and press Enter:

reg add HKLM\Software\Policies\Microsoft\office\16.0\common\officeupdate /v updatebranch /t REG_SZ /d BetaChannel 3. After you add the registry key, select File> Office Account > Update Options, then Update Now to initiate the switch to Beta Channel.

I only use an external monitor (2.560x1.440), and my integrated display (which I don't use in dock) has the same resolution.

According to DXDiag, I have DirectX 12, the main driver is dated 20210820, and no problems had been detected.

I'm quite sure that it's not a question of versions, options etc., because 2405 has not this bug, but later versions have.

So far, I cannot cause the GPU to spike. I tested switching mail to calendar and otherwise. Does this happen on the primary monitor or is it secondary or does it matter?

In the past when we looked into graphics issues engineers would get a DXDiag report, Which version of DirectX is on your PC? - Microsoft Support. This will show you the driver date which could help indicate if the driver is old and needs to be updated.

Another thing to test if it would help is the option File, Options, General, User interface options, Office support for high definition displays - Microsoft Support. Test with best appearance and optimize for compatibility.

Dear Gabriel,

the GPU (not CPU) bug happens too often now: I cannot restart Outlook 5-10 times times every day to stop the GPU from running perpetually, so that I preferred to do the rollback to 2405 again instead of SemiAnnual Channel. My productivity went down too much checking and taking care all the time of this bug.

2405 reacts really very much quicker than the later versions incl. SemiAnnual Channel 2408 which have been slowed down extremely: When you switch from mailbox to calendar or from inbox to sent mails, for example, it takes nearly a few seconds for each click (and sometimes the GPU starts running with high load without any end [Task DWM.exe in Task Manager], until you quit Outlook - or put other windows over Outlook, but as soon as Outlook is on top again, the CPU load continues), whereas 2405 reacts on the spot without delay.

This seems to be a separate bug, because even SemiAnnual Channel, which has not the CPU bug, is concerned by the GPU bug.