Typing on Classic Outlook is hogging PCs with high CPU usage, Microsoft shares workaround

The Microsoft 365 support team must have had a busy time this last week, as the company has been faced with multiple outages, with the latest one being Teams failing to share files.

Meanwhile, the Classic Outlook app is also suffering from buggy updates as Microsoft recently broke downloads. Another bug has hit the Classic Outlook app now, and this one is causing high CPU usage often as high as "30 to 50%," leading to system hogging and performance issues.

This is happening when typing, indicating that it is most certainly a bug, as something like typing should never be that intense unless you are still running a Pentium 4 or an original Athlon or something like that.

Microsoft has explained the issue below:

ISSUE

When you write an email in classic Outlook for Windows, you may notice the CPU spikes up to 30 to 50% at some times and increases the power consumption. You can observe this if Task Manager is open while you type.

This issue can occur after updating to Version 2406 Build 17726.20126+ on Current Channel, Monthly Enterprise Channel, or the Insider channels.

Microsoft has also offered a workaround for the bug, and it involves switching to the semi-annual channel, which does not appear to have this issue, although there may be other minor ones. The company has explained how to do so using either the Office Deployment Tool or by Registry edits.

It writes:

STATUS: WORKAROUND

The Outlook Team is investigating this issue. We will update this topic when there are any status updates.

To work around the issue, you can switch to Semi Annual Channel where the issue has not been observed. You can switch to Semi Annual Channel using one of these methods:

Office Deployment Tool

Follow the steps in the Change the Microsoft 365 Apps update channel for devices in your organization article to switch to Semi Annual Channel.

Use a registry command

Use a registry key to switch to Semi Annual Channel:

1. Open a Command prompt window (ensure Run as administrator was selected).

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 SemiAnnual

3. After you add the registry key, select File > Office Account > Update Options > Update Now to initiate the switch to Semi Annual Channel.

For more insights, go to this forum thread: High CPU usage when typing a message in Outlook.

You can find the support article here on Microsoft's official website.