Speed Up Slow Microsoft Outlook Application: Fix Lag, Freezing & Performance Issues

Why Is My Outlook Running Slow?

Below are some more points that explain what other possible reasons could be.

• An oversized PST or OST file: Outlook stores everything locally in one of these files, and once it grows large, reading through it becomes noticeably slower.
• Too many add-ins: Each one uses memory and processing time at startup. In spite of being disabled, they run in the background and use memory.
• An outdated version of Outlook or Windows: Updates that have not been installed can leave known performance problems unresolved.
• Large amounts of emails: Files that are larger in size consist of many sub-folders, which Outlook loads every time that folder is opened.
•  Low RAM and insufficient disk space: Outlook consumes more system resources for better performance, affecting running applications because of limited system resources.
• File attachments: Bigger attachments that come with emails increase the file size, which makes Outlook laggy.

Quick Inspections Before Troubleshooting

Before moving further, a quick check is worth it to understand why “Outlook running slowly”:

• Check your internet connection for stability, as a poor connection might slow down Outlook, and it might feel laggy.
• Clear the cache because it can cause temporary glitches, and Outlook becomes slow. Therefore, clear the cache before restarting Outlook.
• Update Windows and Outlook because Microsoft regularly patches to reduce the occurrence of these issues.

How to Speed Up a Slow Microsoft Outlook Application?

If your Outlook is still slow or unresponsive after going through the above section. Below are some points to speed up slow Microsoft Outlook application.

1. Remove Unwanted Add-ins

Add-ins are mini programs that are connected to Microsoft Office to extend the functionality of the software. Many add-ins instantly load as soon as the program starts. If any add-in is not currently used, they are still active in the background. That’s why remove or disable unused add-ins. This is the fastest and easiest way to fix Outlook lag issues.

To disable add-ins, follow the steps below.

1. Open Microsoft Outlook, then click File → Options from the left-side menu.
2. In the Options window, click Add-ins on the left panel.
3. At the bottom, click the Manage drop-down.
4. Now, select Add-ins, and click Go.
5. A pop-up will appear containing add-ins—uncheck those you don’t actively use.
6. Click OK to save the changes, then exit Outlook.
7. Reopen Outlook to check if Outlook is working fine.

2. Compact the PST and OST Files

Deleting emails does not shrink the data file itself. The empty space stays there until the file is compacted. Therefore, to speed up slow Microsoft Outlook application:

1. Open Outlook again and navigate to File → Account Settings.
2. And select Account Settings again from the drop-down menu.
3. After that, click Data Files to see a list of all PST and OST files
4. Click on the PST file you want to compact.
5. Click Settings, then click Compact Now.

3. Clean Up or Archive the Mailbox

Sometimes you might feel that your Microsoft Outlook has started running very slowly. This could be because of your mailbox. A mailbox that has grown large in size causes a load on Outlook every time it opens. You can reduce the file size by these below given steps.

1. Open Outlook again, navigate to the File tab → Tools, and select Mailbox Cleanup.
2. Now, click View Mailbox Size to see folder size.
3. You can use the Find items older than option to locate old emails.
4. Click Empty Deleted Items to permanently delete them.
5. Use AutoArchive (or File → Tools → Clean Up Old Items) to move them into a separate archive folder.

4. Create a New Outlook Profile

If none of that works, the profile might be the main issue.

1. Exit Outlook before making any changes to profiles.
2. Open the Control Panel, then search for and click Mail (Microsoft Outlook).
3. In the Mail Setup, click Show Profiles, then click Add to create a new profile.
4. Follow the wizard to set up your email account under this new profile.
5. Then, select the new profile, choose Always use this profile, and set it as the default.
6. Then click OK and reopen Outlook.

A corrupted profile can drag down performance that is hard to trace back. This could help you to troubleshoot performance issues in Outlook.

5. Repair the Data File with ScanPST.exe

Sometimes the file size is not an issue. It is because of corruption inside the PST or OST file. To repair corrupted PST file issues and speed up slow Microsoft Outlook application, follow these steps.

1. Close Outlook completely.
2. Locate ScanPST.exe inside your installation folder.
3. Open ScanPST.exe, then click Browse.
4. Select the PST or OST file you want to check.
5. Click Start to begin the scan.
6. If errors are found, click Repair to fix them.

The Outlook Inbox Repair Tool can handle minor corruption easily. It struggles once the damage increases.

6. Using the Aryson Outlook PST Repair Tool

There are certain cases where the Inbox Repair Tool of Outlook could fail to solve the problem. In these situations, use the Aryson Outlook PST Repair Tool to fix your PST file. It doesn’t rely on Outlook to repair your PST file. It can easily repair corrupt and inaccessible files. You also get a load & save option to save a snapshot to avoid re-scanning the PST file.

Key features of the Aryson Outlook PST Repair Tool

Here are some of the key features, which are listed as follows:

1. Fixes corrupt/inaccessible PST files—retains the recovered emails, contacts, calendar, tasks, notes, and journal exactly.
2. Handles encrypted & password-protected PST files—works with PST files with high encryption, low encryption, and no encryption. Also handles alignment errors and high compaction.
3. Three PST repair modes—Standard (minor corruption), Advanced (moderate corruption), and Deep (severe corruption).
4. Doesn’t depend on ScanPST.exe or Outlook—functionality assured even if the MS Inbox Repair Tool fails.
5. Fixed oversized PST files—No PST file size limitation for corrupted PSTs.
6. Multiple saving options—export recovered PST emails, etc., as PST, EML, MSG, DBX, or MBOX.

Step-by-step guide to use the Aryson Outlook PST Recovery Tool

Below are some points to recover and restore corrupted files.

1. Download and install the Aryson Outlook PST Repair Tool & open it with admin rights.
2. Click on ‘Open‘ to load your corrupted PST file and choose the required recovery mode.
3. Choose the 32-bit or 64-bit version>> then click ‘OK‘ to start the scan process.
4. After scanning, select the required folders/maiboxes to recover.
5. Click Save >> choose the required output format and apply filters.
6. Choose the destination location & click OK to save the recovered PST file.

Conclusion

Outlook can slow down due to several common reasons. Some of the common reasons are add-ins, the size of the file, and insufficient space. Walking through some solutions, such as disabling add-ins, cleaning the mailbox, and compacting the file, works more smoothly. In most of the scenarios, the general problem is corruption that cannot be addressed by manual ways.

Frequently Asked Questions

About The Author:

Harshita Sachdeva

Harshita Sachdeva, a professional technical writer at Aryson Technologies, specialize in delivering clear, hands-on documentation for data management, migration, and recovery solutions. With a meticulous, reader-first approach, I break down complex technical processes into simple, actionable content - helping IT professionals and decision-makers tackle challenges efficiently.

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