High CPU usage when typing a message in Outlook

Is this issue also present in the New Outlook app?

I only use classic Outlook, so I don't know.

Is this issue also present in the New Outlook app?

The Word team implemented a fix and it will go to the Beta Channel with build 18822.15000. That build was just created so it will probably go out to Beta late next week at the earliest. It will go to Current Channel Preview and CC starting with build 18827.20000. CC Preview will get the fixed build in about two weeks. CC will get the build in late May. It's possible the Word Team will backport the fix after it has time in the Insider Channels and after it goes to CC.

I'll update the Known Issue with the fix status as soon as I get a chance.

I don't know it it's just a coincidence, but I currently also have massive GPU (not CPU) usage from Desktop Window Manager parallel to using Outlook. So now Outlook as well as DWM make my system very slow nearly always when I work something.

With the rollback to 2405 this bug was gone, but with SemiAnnual Channel (2408), it's there again: Outlook also causes high GPU (not CPU) load of about 30-60% by the task "Desktop Window Manager" when Outlook is visible and not overlapped by other windows. Often it helps to quit Outlook and to start it again, but sometimes, this has to be done even several times. This normally does not make the fan work, but it makes Outlook significantly slower all the time.

@Gabriel Bratton, could you maybe also reproduce this and report it to the right place at Microsoft?

What's strange: The bug appears since version 2406 which was published in June 2024, but why did the CPU spikes during typing e-mails start around November 2024 and not already before? There seems to be a second condition which was not fulfilled before November?