Microsoft has confirmed plans to address a known issue causing significant CPU spikes when users type messages in recent versions of the classic Outlook email client. The problem, first reported by users in early November, causes CPU usage to jump to 30-50% during typing, resulting in increased power consumption.

## Issue Details

The bug affects users in the Semi-Annual Channel who have updated to Outlook Version 2406 Build 17726.20126 or later. Despite user attempts to disable spell-check options and add-ins, the CPU usage problems persist.

“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,” Microsoft explained in a support document update.

## Fix Timeline

Microsoft plans to roll out fixes according to the following schedule:
– Beta Channel (Version 2505 Build 18822.15000): Early May 2025
– Current Channel Preview (Version 2505 18827.20000): Mid-May 2025
– Current Channel (Version 2505 18827.20000): Late May 2025

## Temporary Workaround

Until the fix is available, affected users can temporarily revert to Version 2405 by:

1. Locating the appropriate Version 2405 build from the Microsoft 365 Apps update history
2. Opening Command Prompt as Administrator
3. Running the command: “%programfiles%Common FilesMicrosoft SharedClickToRunofficec2rclient.exe” /update user updatetoversion=16.0.17628.20144 (replacing the build number as needed)

Alternatively, users can utilize the Office Deployment Tool to revert to earlier Office versions.

Microsoft cautions that reverting is “not recommended since there have been security updates since that version,” but acknowledges it as the only workaround for those urgently needing a solution.