How To: Improve the performance of Microsoft Outlook

Outlook Booting Up

Microsoft Outlook has so far exceeded my expectations as the email client works fantastically in Windows 10 but, as with most other programs, it can be optimized for better performance. This is especially true for email clients as the more you use them, the more data they have to handle which can make them sluggish and unresponsive which is the last thing you want when you are dealing with mail.

Check Windows updates

You may not know this but Microsoft delivers most Office patches through Windows Update so if you never download and install updates, Outlook will undoubtedly perform worse than it could. Newer versions which are connected to the Internet also receive updates automatically from Microsoft. You can check the version of your Outlook by going to File > Account.

Office Updates

There will be a section named Office Updates with a description that says whether you are receiving automatic updates or not. Finally, you can click on the “Update Now” option to force Outlook to check for updates right away.


When you have thousands of emails that Outlook needs to go through every single time it boots up, there is little doubt that it will get slower as time progresses. Instead of forcing the email client to process all of your emails every day, you can choose to archive old emails. This process will simply take your old emails and place them separately so that Outlook can deal with newer items. Archived emails can always be accessed so it is not like you will lose them, they will just stay out of sight until they are needed.

To do this, click on the File menu and select “Options”. Go to the Advanced tab and click on the “AutoArchive Settings” button. Enable the feature by checking the very first box and then click on OK to use the default settings. If you do not make any changes, AutoArchive will run every 14 days and it will archive emails older than 6 months. Personally, I archive emails older than 3 months as there is little chance I will need to quickly access anything that old.

Outlook AutoArchive

To change AutoArchive settings for individual folders, select them in Outlook and go to the Folder tab. Then, click on the “AutoArchive Settings” button and change whatever you want.

Outlook AutoArchive Settings


Like the rest of Microsoft’s Office apps, Outlook includes a host of add-ins that aim to introduce new features or make your life easier. Every single last one of these add-ins is completely optional and can be safely disabled so the app can launch faster. There is no reason to keep additional items that you never use, especially since they can easily be enabled again in the rare occasion that you will need them.

Outlook Add-ins

Click on the File menu, go to Options and visit the Add-ins tab. At the very bottom of the window you will see a dropdown menu that should have “COM Add-ins” selected. Click on the “Go” button next to the menu and you will see a list of add-ins that you can enable or disable at will. Just remember to click on “OK” to save your settings and close the window. I would not recommend removing an add-in unless absolutely necessary as disabling them works just fine.

Cached Exchange Mode and the PST File

Outlook can operate in one of two modes: Online or Cached Exchange. In the Online mode, the email client connects itself to Microsoft’s servers and instantly retrieves incoming communications. In the Cached Exchange mode, Outlook creates an Offline Storage Table (OST) file where it caches your mailbox. This means everything is always accessible offline though new emails may take a few more seconds to arrive. Furthermore, the offline mode can improve the performance of computers with slow Internet connections so the choice depends on what your computer can handle best.

Should you choose to run your accounts in Cached Exchange mode, you may need to reduce the size of the OST file. As you use the application, this file gets bigger and bigger as more data is added to it which results in Outlook getting slower as a whole. Archiving your emails is perhaps one of the best ways to combat this but you can also choose to compact the file so that Outlook can process it faster.

Click on the File menu and select the Account Settings option from the Info tab. Once the “Account Settings” window opens, go to the Data Files tab and double-click on one of your accounts. Depending on your account settings, you may instantly get the option to “Compact Now” so just click on that and you are done.

Outlook Compact Now

For Microsoft Exchange accounts, head over to the Advanced tab after double-clicking on the account. Click on the “Outlook Data File Settings” button to open the synonymous window and you will be able to select the “Compact Now” option.