Overview

• Microsoft has acknowledged a bug in Outlook Classic that causes CPU usage to spike by 30–50% when typing emails, leading to slowdowns and overheating.
• The issue impacts Outlook Version 2406 Build 17726.20126+ on the Current, Monthly Enterprise, and Insider channels, but not the Semi-Annual Channel.
• Affected users have reported ineffective troubleshooting attempts, including disabling add-ins, spell-check, and graphics acceleration.
• Microsoft recommends switching to the Semi-Annual Channel as a temporary workaround, with detailed instructions provided for both enterprise and home users.
• The Outlook Team is actively investigating the problem, which has been reported since November 2024, but no permanent fix has been announced yet.