[Fixed]: Outlook is Running Slow on Windows 10/11

Summary: Outlook is running slow is an issue that can occur due to various reasons, such as sync issues or corrupt PST file. In this guide, you will learn the reasons that can cause Outlook to slow down and solutions to troubleshoot and fix the Outlook performance issue. You will also get to know about an advanced PST repair software that can help to quickly recover all mailbox items from corrupt PST file.

Outlook is running slow on Windows 10 or 11 system is a common issue that may occur due to several reasons. It can lead to loss of productivity and delays in sending or receiving new emails. You may also fail to access, open, or join a meeting on time which can have severe consequences on your reputation, work, and business.

Some of the common symptoms of Outlook slowdown that are reported by users include frequent Outlook freeze, Outlook taking time to load, Outlook stuck on the load screen, and delays in loading search results or executing basic tasks.

If you’re facing any of these problems, then follow the solutions and tips shared in this guide to troubleshoot and resolve the Outlook is running slow issue.

Reasons for Outlook Running Slow?

Several reasons can lead to Outlook performance issues. These include:

• Large mailbox size (Outlook Data file)
• Incompatible or faulty Outlook add-ins
• Outdated Outlook or Windows
• Corrupted Outlook data file (PST)
• Insufficient hardware, such as RAM or processor
• Corrupt Outlook profile

How to Fix Outlook is Running Slow Issue on Windows 10/11?

You can follow the below solutions to troubleshoot and resolve the Outlook running slow issue. 

1. Check Hardware Resources

If you are someone who uses Outlook for sending and receiving several emails and attachments daily, consider upgrading the hardware. Consider the following:

• Upgrade RAM
• Replace traditional HDD with solid-state drive (SSD)
• Change system to a better one with the latest multi-core processor and other hardware.

2. Update Outlook and Windows

Ensure your Outlook and Windows are up-to-date. Microsoft regularly releases updates to fix bugs, introduce new features, and improve performance. Follow the below steps to check and apply the new updates in Outlook:

• Open Outlook and navigate to File > Office Account.
• Click on Update Options and then click Update Now.

• Outlook will check for new updates. If available, download and apply those updates to your Outlook. This will help fix the Outlook bugs and may resolve the Outlook running slow issue.

If you do not find the option to update Outlook, it might be locked or disabled by your administrator. In such a case, you can check and install the Windows updates. Windows updates not only bring bug fixes for Windows OS but also for other Microsoft applications, such as Outlook. The steps to install Windows updates are as follows:

• On your Windows 10 or 11 system, open Settings and go to Update & Security.
• Click Windows Updates.

• Click Check for Updates. If new updates are available, download and install them.
• Once the process is finished, restart the system.

3. Disable Add-ins

Incompatible or faulty add-ins are one of the common causes behind Outlook performance issues. Therefore, disable the add-ins to check if that resolves the issue. The steps are as follows:

• Close Outlook and open the Run dialog box by pressing Windows + R.
• In the Run dialog box, type outlook.exe /safe and press the Enter key or click the OK button to start Outlook in safe mode.
• Then go to File > Options and select Add-ins.
• Click the Go button at the bottom. It’s located next to Manage Add-ins.
• In the COM-Add-ins dialog box, uncheck all checkboxes of the add-ins and then click OK to disable the add-ins.

• After disabling the add-ins, close Outlook Safe Mode and restart Outlook normally.

Check whether the Outlook is running slow problem is resolved.

4. Reduce Mailbox Size

A large-sized Outlook mailbox is one of the common reasons for Outlook performance issues. So, you must reduce the mailbox size by archiving old emails, deleting large attachments or emails after backup, deleting unnecessary mail items, and emptying the Deleted Items folder. Here’s how you can reduce the mailbox size:

1. In Outlook, go to File > Info > Tools and click Mailbox Cleanup.
2. Click View Deleted Item Size and then click Empty to permanently remove all the deleted mail items.
3. Beside View Conflict Size, click Empty to delete all alternate versions of items in your mailbox.
4. Then, use the Find button to either Find items older than or Find items larger than. This helps you delete old emails and emails larger than a certain size.
5. To archive old mail items, go to File > Info > Tools and click Clean up old items.
6. Select the mail folder or email account you want to archive.
7. Choose data from the Archive items older than dropdown and click Browse to select a location to save the archive file (local .pst).
8. Then click OK. This will move all the emails that are older than the selected date to a local PST file. You can continue to access your mail items from the archived PST file.

Once the size of the mailbox is reduced, restart Outlook and check if the performance has improved.

5. Change Outlook Settings

You may also adjust some settings in Outlook to improve Outlook performance. Here’s how:

• In Outlook, go to File > Options > Advanced.
• Under the Other section, disable Use animations when expanding conversations and groups.

• Click OK.

6. Repair Outlook Data File

Corruption or inconsistencies in the Outlook data file (PST) can cause various issues, including the Outlook is running slow issue. However, you can use the Inbox Repair tool (SCANPST.EXE) in Outlook to repair the PST file. The steps are as follows:

• Launch the SCANPST.EXE program which is located in the C:\Program Files\Microsoft Office/Officexx or C:\Program Files\Microsoft Office/root/Officexx folder.

• On the Microsoft Inbox Repair Tool, click Browse to choose the PST file, which is stored in the %localappdata%/Microsoft/Outlook folder.
• After selecting the PST file, you need to click the Start button.

• If the tool finds errors and inconsistencies, click Repair.

Note: The tool will create a backup of the original PST file (.bak extension) and then try to repair the original PST file. This process may take a while to complete. The time depends on the level of corruption, inconsistencies, or errors, and the PST file size.

• Once the PST file is repaired, start Outlook.

Since the PST has no errors or inconsistencies, Outlook should perform well and run stable and fast.

In some cases, the Inbox Repair tool (SCANPST) crashes, stop responding, or fail to repair the PST file. This happens when the PST file you are trying to repair is larger than 2 GB, severely corrupt, or encrypted. The SCANPST can’t repair such PST files.

To repair such PST files, you need advanced Outlook PST repair software, such as Stellar Repair for Outlook. The software can repair severely corrupt, damaged, inaccessible, large-sized (even 50 GB or larger), and encrypted PST files with complete integrity and precision.

The software saves all the recovered mail items to a new PST file and provides an option to directly export all the recovered mail items from the corrupt PST file to Microsoft 365 (Office 365) or Exchange Server in a few clicks.

7. Create a New Outlook Profile

Sometimes, the Outlook profile gets damaged or corrupted, causing Outlook’s slow performance. In such a case, you can create a new profile to resolve the underlying issues related to the profile. Here are the steps:

• Close Outlook and open the Control Panel.
• Click User Accounts > Mail and then click Show Profiles > Add.
• You need to enter a name for this new profile and then click OK.

• Follow the login wizard and set up your same email account under this new profile.
• After the setup, you can make this profile as the default profile.
• Then, launch Outlook.

• You may also remove the old profile to avoid confusion.

Once done, check if the Outlook performance issue is resolved.

Conclusion

If your Outlook is running slow, freezing, or otherwise underperforming on Windows 10 or 11, you can follow the solutions discussed in this guide to troubleshoot the issue and improve the performance of Outlook. Remember to use an advanced Outlook PST repair software, such as Stellar Repair for Outlook when the PST file can’t be repaired using the SCANPST program. The tool can help you recover and restore all mail items from corrupt, inaccessible, or large-sized PST files to a new healthy Outlook PST file.

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