Microsoft to fix CPU spike bug plaguing Classic Outlook in May

If you have been dealing with CPU usage spikes when typing emails in the Classic Outlook for Windows, you’re not alone. However, you’d be happy to hear that Microsoft will soon fix it.

The infamous Outlook bug reportedly spikes CPU usage by 30 to 50 percent. It has affected the version 2406 build 17726.20126 and later, on the Current, Monthly Enterprise Channel, Insider, and Semi-Annual channels.

Microsoft says it will roll out a fix for the CPU spike bug plaguing Classic Outlook in Windows

Microsoft addressed the Classic Outlook’s CPU spike bug last week. It noted that you “can observe this if Task Manager is open while you type.” As one would expect, many users relying on Outlook for daily communication were fuming over this bug.

The good news is that Microsoft’s Word team has reportedly developed a fix for the CPU spike bug. The same will roll out in phases throughout May 2025. The fix will debut in the Beta Channel (version 2505, build 18822.15000) in early May 2025.

In mid-May, Microsoft will roll out a fix for the CPU spiking bug to the Current Channel Preview (version 2505, build 18827.20000). Regular Current Channel users, the largest group, will receive the update by late May. 

You can revert to the previous version for an immediate fix

If you are looking for an immediate fix to curb the CPU spike bug, Microsoft hints at reverting to version 2405. However, it further warns that doing so skips critical security updates. If you still wish to do it, follow the steps suggested by Microsoft:

1. Locate the build of Version 2405 for the respective channel you are on from Update history for Microsoft 365 Apps (listed by date) – Office release notes.
2. Open a Command Prompt (Run as Administrator).
3. Type or past the command below and put the build from Step 1 and then press Enter: “%programfiles%\Common Files\Microsoft Shared\ClickToRun\officec2rclient.exe” /update user updatetoversion=16.0.17628.20144

Alternatively, Microsoft says that “you can use the Office Deployment Tool to switch to an earlier version of a channel.” You can get a detailed guide on how to revert to an earlier version of Office by clicking here.