Introduction

Microsoft Outlook has long been a cornerstone for email communication and personal information management. However, users of the classic Outlook for Windows have recently encountered significant performance issues, notably high CPU usage and application crashes during email composition. This article delves into the causes of these problems and offers effective solutions to restore optimal functionality.

Understanding the Issue

Symptoms

Users have reported that while typing emails in classic Outlook for Windows, CPU usage spikes dramatically, sometimes reaching 30% to 50%. This surge not only slows down the application but also increases power consumption, leading to potential system instability.

Affected Versions

The issue predominantly affects users who have updated to Outlook Version 2406 Build 17726.20126 and later on the Current Channel, Monthly Enterprise Channel, or Insider channels. Notably, the problem has also been observed in the Semi-Annual Channel following updates to the same build.

Root Causes

Several factors contribute to these performance issues:

  1. Software Updates: Recent updates to Outlook have introduced bugs leading to increased CPU usage during email composition.
  2. Add-ins and Extensions: Third-party add-ins can conflict with Outlook's operations, causing resource spikes.
  3. Search Indexing: Corrupted or inefficient indexing processes can lead to excessive CPU load.
  4. Large Mailbox Size: Extensive mailboxes can slow down Outlook's processing capabilities.
  5. Corrupted Data Files: Damaged PST or OST files can result in performance degradation.

Implications and Impact

High CPU usage and frequent crashes in Outlook can severely disrupt productivity. Users may experience delays in email communication, system slowdowns, and increased power consumption. For organizations, these issues can lead to operational inefficiencies and increased support costs.

Effective Solutions

1. Switch to Semi-Annual Channel

Microsoft recommends switching to the Semi-Annual Channel, where the issue has not been observed. This can be achieved using the Office Deployment Tool or by adding a specific registry key.

Using the Office Deployment Tool:
  • Follow the steps outlined in Microsoft's support article to change the update channel for Microsoft 365 Apps.
Using a Registry Command:
  1. Open Command Prompt as Administrator.
  2. Enter the following command:

``INLINECODE0 `INLINECODE1 File > Office Account > Update Options > Update NowINLINECODE2 File > Options > Add-InsINLINECODE3 COM Add-insINLINECODE4 GoINLINECODE5 OKINLINECODE6 Indexing OptionsINLINECODE7 AdvancedINLINECODE8 Index SettingsINLINECODE9 RebuildINLINECODE10 SCANPST.EXEINLINECODE11 Deleted ItemsINLINECODE12 File > Office Account > Update Options > Update NowINLINECODE13 Settings > Update & Security > Windows Update` and check for updates.

Conclusion

Addressing high CPU usage and crashes in classic Outlook requires a multifaceted approach, including adjusting update channels, managing add-ins, repairing data files, and maintaining an optimized mailbox. By implementing these strategies, users can enhance Outlook's performance and ensure a more stable and efficient email experience.