Fix Slow Outlook Performance Issues | 11 Solutions 

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Outlook slowing down or lagging can be really frustrating. However, in this write-up you will learn 11 easy ways to effectively fix Outlook performance issues. In case of performance issue due to corrupt PST file, we have recommended you to make use of the Remo Repair PST tool to effortlessly resolve the performance issues of Outlook arised from a corrupt PST file.

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Outlook is a reliable and popular email exchange utility used across the globe by many professionals and corporates on a day-to-day basis.

However, you may encounter Microsoft Outlook with some issues when you have lot of items in a single folder. The following problems encounter due to performance issues are discussed below. 

  • 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

How do I Fix the Outlook Performance issue?

  1. Safe mode 
  2. Repair Outlook profile 
  3. Fix Outlook Data file issues 
  4. Maintain your PSTs at a reasonable size
  5. Disable Add-ins that are not in use
  6. Enable Cached Exchange Mode or delete Outlook cache
  7. Repair via Outlook installer 
  8. Create a new Outlook profile 
  9. Disable RSS feeds in Outlook
  10. Use ScanPST.exe 

Why is Outlook so Slow? 

Your Outlook’s performance maybe is affected due to multiple reasons. Which are mentioned in the following sections

  1. Unnecessary Add-ins slowing down your Outlook 
  2. Over-sized PST file affecting the performance 
  3. Due to Faulty third-party extensions 
  4. Exceeding your Outlook item limit 
  5. Corruption of the PST file. 

Fortunately, if you have gone through any of the above-mentioned scenarios, you can effortlessly fix the Outlook performance issues by following the below-listed methods. 

Method 1: Safe mode 

  1. Right-click on the Start button, Click on Run 
  2. Type outlook.exe/ safe and press Enter
  3. Verify if Outlook is still slow, even after entering the Safe Mode. If yes, go ahead with the below-listed solutions 

Method 2: Repair Outlook profile 

  1. Go to Control Panel Open Control Panel on Windows
  2. Click on Email Accounts 
  3. In the options go to Account Settings dialog box and select E-mail tab 
  4. Click on your Outlook profile and select Repair 
  5. Follow the prompts from repair wizard
  6. Click on Finish and restart Outlook 

Method 3: Fix Outlook Data file issues 

  1. Click on Control Panel and select Mail to find the PST file
  2. Click on Data Files
  3. If there is more than one PST file, look for the one with the checkmark (default).
  4. Go to Show hidden files, folders, and drives and uncheck Hide extensions for known file types.
  5. Save a backup copy of the PST file to a safe location or removable storage.
  6. Rename the .pst extension to .psp.
  7. Open Outlook.
  8. Click OK twice when prompted during start-up to create a new PST file.

Method 4: Maintain your PSTs at a reasonable size

With Outlook 2003 and 2007 you can create “new style” PST files that do not have the old 2GB limit. However, for best performance, it is still recommended to keep your PST files relatively small and not let 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

Method 5: 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.

Method 6: Enable Cache Exchange mode 

  • Go File > Account Settings click on account settings
  • Click on Exchange or Microsoft 365, then click on Change 
  • Under Offline settings, check to Use Cached Exchange Mode.
  • Note - if you are not a Microsoft 365 user, click on Use Cached Exchange Mode to download email to an Outlook data file.
  • Restart Outlook and see if you still encounter a performance issue

Method 7: Repair via Outlook Installer 

  1. Go to Control Panel 
  2. Go to Add - Remove programs 
  3. Select Office installation or Outlook application 
  4. Click on Modify or Repair option  select Microsoft Office Professional or Word to repair
  5. Open Outlook and verify if the repair has worked well to resolve your Outlook performance issue 

Method 8: Create new Outlook profile 

Follow the listed steps to create a new Outlook Profile 

  1. Go to File > Account Settings > Manage Profiles 
  2. Here you will come across options like Show Profiles > Add 
  3. In a Profile Name, do not put the same user name of any residing profiles. Add a new user name and create a profile 
  4. Restart Outlook and see if the Outlook performance issue is resolved 

Method 9: Disable RSS feeds in Outlook

  • Go to File > Account Settings 
  • In the options go to RSS Feed tab, under Feed name, click on Remove option  
  • You will be prompted with the deletion option, click on Yes 
  • This will Disable the RSS Feeds in Outlook 
  • Restart the Outlook application and see if your Outlook is still slow

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 using a reliable PST repair tool.

Method 10: Use scanPST.exe to fix the Outlook performance issue and corruption 

ScanPST.exe is a reliable in-built tool that can effortlessly fix Outlook performance issues or even corruption of the Outlook application. scanPST.exe is an effective utility that can resolve any sort of corruption. 

Even if scanPST.exe doesn't work well for you, then there is a severe corruption of the PST file, you will need a reliable repair utility to fix the corruption of the PST file. 

Method 11: Remo Repair PST to repair Corruption of the PST file 

Make use of Remo Repair PST, a reliable data recovery tool bound to fix severe corruption issues. The tool works on a read-only mechanism. Makes a copy of your PST file and works on the copy to make it a workable PST file. PST file created on any version of Outlook including Outlook 2021, 2019, 2016, and its previous versions. This PST file repair tool takes only a few simple clicks to repair PST file. And it recovers also missing Outlook items such as emails, attachments, contacts, folder structure, and rules. Download now and resolve the Outlook performance issues. 

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 count

About the Author: Tony Landry

Tony Landry is a Web Content Editor at Remo Software. He loves to write, edit, and manage content for users trying to troubleshoot and fix problems on Windows, Outlook, storage drives, and Cloud storage networks. With an aptitude that transcends writing, Tony is recognized as a Microsoft Outlook, Word, and PowerPoint expert. His comprehensive solutions…