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How to Fix Outlook Performance Issues?

In Microsoft Outlook, you may encounter some issues when you have lots of items in a single folder. Some of those problems are something like this:

  • When performing certain options using Cached Exchange Mode or an Outlook data (.pst) file, you notice performance issues
  • Also, you experience decreased performance in Outlook if the Inbox, Calendar, Tasks, Sent Items, and Deleted Items folders contain lots of items

Likewise, if you have lots of mail folders, you may experience performance issues like:

  • In cached mode, folders are not displayed correctly, or they take a long time to appear
  • If your Outlook profile has shared mailboxes and has caching enabled, folder synchronization issues, performance issues, and other problems occur if the number of shared folders per mailbox exceeds 500
  • In extreme cases, if there are more than 10,000 folders, Outlook is very slow to open. This behavior occurs because it takes a long time to enumerate the folders

The root cause of the problem –

If you have folders that exceed the limit for the number of items per folder or if you have too many folders total. The item and folder limits depend on the version of Outlook. For Outlook 2016, Outlook 2013 and Outlook 2010, 100,000 items per folder and total 500 folders. For Outlook 2007, you can have maximum 50,000 items per folder and 500 folders total.

How to resolve Outlook Performance Issues?

Well, there are a few simple steps you can take to improve Microsoft Outlook performance. If your Outlook is slow and unstable, it can put a serious drain on your productivity and even elevate the stress level. So take a few moments to get it shape.

Solution #1: Maintain your PSTs at a reasonable size

With Outlook 2003 and 2007 you can create “new style” PST files which do not have the old 2GB limit. However, for best performance, it is still recommending to keep your PST files relatively small and not letting them grow too much above 1GB.

Here are a few things you can do to keep PST files from growing:

  • Use multiple PSTs: Create multiple PST files and organize email into them by date or by project, client, etc.
  • Keep attachments outside of the PST: Large attachments can quickly fill up your PST and make it grow huge. You can save your attachments outside of Outlook and still keep links to them in email messages
  • Save entire email messages outside of Outlook: Save entire messages outside of Outlook and create an email archival system using file folders

Solution #2: Disable Add-ins that are not in use

Running unnecessary add-ins may make Outlook slower. Check what add-ins you have installed. You probably have more add-ins installed than you think. Check what Add-ins you have installed and disable the ones you are not using.

Solution #3: Compact your PST files and OST file (Exchange users only)

After you have split your messages into multiple PST files and removed some of the attachments, you need to compact the PST file to shrink its size. If you are using an Exchange account in Cached mode, compacting your OST file may help improve performance.

However, it is a good idea to compact your PST files periodically.

Recommended: For the users who are experiencing “Outlook PST large but empty” issue. It is suggested to fix the issue by compacting the Outlook data file using Compact Now option, or use a reliable PST repair tool.

Solution #4: Enable Cached Exchange Mode

If you are using an Exchange-based mail account, enabling Cached Exchange Mode will likely improve Outlook responsiveness.

Solution #5: Keep your computer up to date with patches and Service Packs

Use Microsoft Windows Update service to keep up to date with Windows and Office patches and service packs.

Solution #6: Reset Outlook cache files

If you upgraded from Outlook 2003 to Outlook 2007, some people have reported that resetting a few internal Outlook files helps with performance.

Solution #7: Disable RSS feeds in Outlook

  • Open “Tools->Options->Other->Advanced Options
  • Uncheck “Sync RSS Feeds to the Common Feed List

However, you can see how overall client user experience can be affected by these performance issues. Hope the above-mentioned solutions will fix your performance issues that may occur when a mailbox has high item counts and when restricted views are being used.

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John Harris

Senior Editor, Content Analyst and a fan of exceptional customer service. John develops and publishes instructional and informational content regarding partition management, Windows hot-fixes, data management and computer troubleshooting.

As a tenured data recovery specialist, John shares exceptional insights and blog posts about data loss and data recovery across any storage device. With 8+ years’ experience in writing for Data Recovery for both Mac OS and Windows OS computers, he is an avid learner who always wants to polish and simplify the data recovery process. John passes his free time playing Chess and reading Science Fiction novels.

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