Table of Contents
Why Is Outlook Causing High CPU Spikes? Effective Solutions for Frustrated Users
Classic Outlook users have reported significant CPU spikes—ranging from 30% to 50%—when typing emails, leading to slow performance, typing delays, and increased power consumption. This issue has been linked to updates released in June 2024 for Microsoft 365 Apps version 2406 Build 17726.20126 and later, impacting users on the Current, Monthly Enterprise, and Insider Channels.
Symptoms
- CPU usage rapidly increases when typing in Outlook
- Noticeable typing lag and system sluggishness
- Elevated power consumption and potential overheating
Immediate Workarounds
Solution 1: Switch to the Semi-Annual Channel
This method reverts Outlook to a more stable update cycle, avoiding the problematic build.
- Press Windows + R to open the Run dialog.
- Type cmd and press Ctrl + Shift + Enter to launch Command Prompt as administrator.
- Approve the User Account Control prompt.
- Enter the following command and press Enter:
reg add HKLM\Software\Policies\Microsoft\office\16.0\common\officeupdate /v updatebranch /t REG_SZ /d SemiAnnual
- Open Outlook, go to File > Office Account > Update Options > Update Now to apply the channel change.
Alternatively, use the Office Deployment Tool for channel switching.
Solution 2: Roll Back to a Previous Version (Version 2405)
Rolling back to an earlier version can resolve the CPU spike, but note that you may miss recent security updates.
- Identify the build number for Version 2405 from Microsoft’s update history.
- Open Command Prompt as administrator.
- Run:
"%programfiles%\Common Files\Microsoft Shared\ClickToRun\officec2rclient.exe" /update user updatetoversion=16.0.17628.20144
You can also use the Office Deployment Tool to revert to an earlier version.
Microsoft’s Official Response
Microsoft has publicly acknowledged the issue and confirmed that a fix is being developed. The Word team has prepared a solution, which is scheduled for phased release in May 2025:
- Early May: Beta Channel (version 2505, build 18822.15000)
- Mid-May: Current Channel Preview (version 2505, build 18827.20000)
- Late May: General availability for most users on the Current Channel
By following these steps, you can minimize disruptions and restore Outlook’s performance while awaiting the permanent fix.