Outlook is running slow in Windows 10/11 and Mac? Fix it now

by Milan Stanojevic
Milan Stanojevic
Milan Stanojevic
Windows & Software Expert
Milan has been enthusiastic about PCs ever since his childhood days, and this led him to take interest in all PC-related technologies. Before joining WindowsReport, he worked as... read more
Affiliate Disclosure
  • Outlook is one of the most popular email services in the world that has been providing quality email management features for years
  • Many users are complaining though, that Outlook is moving slow and in this article, we are exploring some ways to fix that.
  • You will learn below how to open Outlook in safe mode, how to fix the data file errors, repair your Outlook Profile, and more.
  • On top of that, we suggest third-party email client alternatives that may work better for you.
fix Outlook is running slow in Windows 10

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Email is a critical part of our daily lives, whether as individuals or even in business, and for IT admins or managers if emails are down, it can be challenging because it disrupts communication.

Outlook is currently the de facto standard email client in the corporate world, which generally works pretty well, but, all this doesn’t come without challenges in its workings.

When Outlook has performance issues, it can be caused either by a corrupt or damaged PST file, an add-in that isn’t functioning, a corrupt profile, or a problem with the Outlook application.

In this article, we are presenting how you can fix Outlook running slow in Windows 10, so keep reading.

How do I fix a slow Outlook on Windows 10?

  1. Open in Safe Mode
  2. Fix Outlook Data File error
  3. Repair the Outlook Profile
  4. Create a new Outlook Profile
  5. Repair Outlook via the Installer
  6. Remove whatever causes the PST to bloat up
  7. Disable RSS feeds
  8. Download complete items
  9. Update Windows
  10. Reduce calendars
  11. Use cached exchange mode
  12. Archive inbox messages
  13. Keep PST file compact
  14. Disable add-ins
  15. Try third-party alternatives

1. Open in Safe Mode

  1. Right-click Start, select Run.
  2. Type outlook.exe /safe and press Enter.
  3. If Outlook is slow in Safe Mode, then an add-in could be causing the issue.
  4. Click File and select Options.
  5. Click add in’s and scroll down to Manage.
  6. Click Go, and on the next screen displayed, remove the checkmarks.
  7. Disable all add-ins.

2. Fix Data File errors

  1. Click Control Panel and select Mail to find the PST file.
  2. Click the 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 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.

3. Repair the Outlook Profile

  1. Open Control Panel and select Mail.
  2. Click on E-mail Accounts.
  3. In the Account Settings dialog box, go to E-mail tab.
  4. Highlight your account, and click Repair.
  5. Follow any prompts from the repair wizard.
  6. Click Finish.
  7. When the repair is done, restart Outlook.

You can also copy the existing profile and see if it opens:

  1. Open Control Panel and select Mail.
  2. Click Show Profiles and select Copy.
  3. Enter a new name for the profile.
  4. Select your new profile from the Always use this profile button.
  5. Click OK.
  6. Restart Outlook.

4. Create a new Outlook Profile

  1. Open Control Panel and select Mail.
  2. Click Show Profiles.
  3. Click Add, enter the name of the new profile.
  4. Select Prompt for a profile to be used then click OK.
  5. Start Outlook, and select the new profile.

5. Repair Outlook via the Installer

If none of the above steps worked, then your Outlook is probably damaged. You can repair Outlook by choosing Change in Apps and features (right click Start and select Apps and Features).

If this and the other methods above fail, you have to uninstall and reinstall Outlook/Office.

6. Remove whatever causes the PST to bloat up

reinstall outlook
  1. Find a folder called Larger than 100 Kb
  2. Delete all unwanted old emails (with bulky attachments).
    • Save attachments you need to the disk but remove them from the PST.
  3. Delete all other unwanted emails.
  4. Clear out the Trash.
  5. Archive your emails by year to relieve the PST file.

7. Disable RSS feeds

Outlook syncs RSS feeds from Internet Explorer by default, to its RSS reader, so if you have many bookmarked feeds, the syncing could slow down Outlook.

Go to Options and in the Advanced tab disable this feature by unchecking both options under the RSS feeds.

8. Download complete items

Outlook should be set up to download full and complete messages when connected with IMAP or POP3, so that it doesn’t have to sync with the server each time you click on a new email or item.

Look for the Download Complete Item Including Attachments setting to enable this.

9. Update Windows

Windows Updates for Office are also ‘hidden’ so you need to allow these to install because sometimes Microsoft updates Exchange, and this can break or cause issues with the Outlook-Exchange communication.

Check also for patches issued by Microsoft for Outlook to resolve speed issues or other problems.

10. Reduce calendars

Outlook running slow in Windows 10 can be worsened by more data, which Outlook is forced to pull from the Internet, so it drags.

You can have one or two shared calendars, but more data means a sluggish Outlook.

11. Use Cached Exchange Mode

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This takes the data file from the PST and caches it on your OST, hence speeding up Outlook as it won’t have to read its data file via a network, but through a locally stored data file.

However, you can only enable this option when connecting Outlook with Exchange server.

12. Archive inbox messages

Millions of email users, including Outlook, have thousands of emails – usually unread – in their inbox, which can cause serious problems when using PST files. You can set up auto-archiving so that the Inbox only retains some of those many emails.

Keep current and previous months’ emails in your Inbox folder, and the rest of them, just archive. This creates a new data file, which relieves Outlook of having to strain from an oversized PST/OST file.

13. Keep PST file compact

  1. Go to Account Settings and click on Data files.
  2. Select the data you want to compact.
  3. Click Settings and choose Advanced.
  4. Click Outlook Data File Settings.
  5. Click Compact Now.

14. Disable add-ins

  1. Open Outlook and go to Options.
  2. Click Add-ins and select COM add-ins.
  3. Click Go.
  4. Find the suspect add-ins and uncheck their corresponding boxes

15. Try third-party alternatives

If you cannot fix Outlook running slow issues or you simply want a good email client, we would strongly recommend Mailbird – Winner of Most Popular Mail Alternative 2021.

A leader on the market, it will satisfy all your needs in mailing management.

The fact that it can handle multiple e-mail accounts so you will be able to add more than the Gmail account to your list, is a great advantage that makes Mailbird the choice of so many users.

Moreover, you can integrate your Google Calendar and Twitter into Mailbird.

Online privacy is extremely important, especially when it comes to emails, and the fact that this software encrypts all the emails that are sent out makes it even more amazing.

There are other options available as well. We recommend looking into the best Windows 10 email client apps because they provide plenty of useful features.

Many up-to-date email clients double as task management systems and integrate advanced search functions, automated emails, digital signatures, and more.

What can I do if Outlook is running slow on Mac?

  1. Select Outlook and click on Preferences.Outlook menu with Preferences highlighted
  2. From the Personal Settings, click the General button, pictured as a switch.
  3. Go to the Sidebar and remove the checkbox for Hide On My Computer folders.
  4. Now look at the the bottom of the sidebar and select the Mail option.
  5. Next, select the messages that you want to move by holding down the Menu key while you select them.
  6. You can drag the messages now to the On My ComputerInbox folder. Keep in mind that after you move the messages to your Mac, they will no longer available when you access your account from a different computer.

This issue on Mac may be due to a slow sync with the mail server because there are too many messages. The solution is to move them on your machine by using the solutions above.

If the email client is not functioning at all, we have an extensive guide on how to fix Outlook if it’s not working on Mac.

Were you able to fix Outlook running slow in Windows 10 using the solutions above? Let us know in the comments section below.

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