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My desktop outlook calendar is very slow to respond to any action - creating events, switching to a new date, etc. I tried all of the usual fixes - can someone help me speed it up?

Anonymous
2025-07-04T16:08:26+00:00

My desktop outlook calendar is very slow to respond to any action - creating events, switching to a new date, etc. I tried all of the usual fixes - can someone help me speed it up?

Outlook | Windows | Classic Outlook for Windows | For home

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  1. Anonymous
    2025-07-04T16:31:11+00:00

    Dear Andy Hannah,

    Thank you for reaching out regarding the issue with your desktop Outlook calendar being slow when creating events or switching dates.

    We truly appreciate that you’ve already tried the usual troubleshooting steps. Since we’re not able to see exactly which methods you’ve attempted, we kindly ask for your understanding as we share a list of advanced solutions below. If any of these overlap with what you’ve already tried, please feel free to skip them.

    1. Start Outlook in Safe Mode (outlook.exe /safe) to check if add-ins are causing the issue. If performance improves, disable add-ins one by one to identify the culprit.
    2. Update Outlook to the Latest Version to ensure you have the most recent performance fixes, including the typing lag and CPU spike bug resolved in May 2025.
    3. Clear Calendar Cache: Right-click your Calendar → Properties → Clear Offline Items → OK → then perform a Send/Receive. This will re-sync fresh data from the server.
    4. Create a New Outlook Profile or delete and rebuild the OST file if the local data is suspected to be corrupted or oversized.
    5. Limit the Number of Shared Calendars Open and disable caching for shared folders if not needed.
    6. Enable “Shared Calendar Improvements” if using a supported Outlook version to improve sync speed for shared calendars.
    7. Test Network Connection: If Outlook runs faster in offline mode, the issue may be related to server communication. You can work offline and sync periodically as a workaround.

    Please note that our initial response may not resolve the issue immediately. However, with your cooperation and more detailed information, we can work together to identify the best solution. 

    Important: To comply with forum policies and protect confidential information, please provide the requested details through the "View Direct Messages" section above. 

    Steps to access View Private Messages: 

    1. Sign in to Microsoft Community with the email account that was used to post this thread.
    2. Click your profile icon in the top right corner of the page.
    3. Select My Profile to access private messaging options.

    I look forward to your response and I look forward to hearing from you soon so that we can continue to work towards a resolution. 

    Best regards 

    Ryan-N-MSFT | Microsoft Community Support Specialist

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  1. Anonymous
    2025-07-07T19:12:55+00:00

    I am having the same issue. Emails etc. are fine. In calendar mode however, it becomes laggy and slow to respond. Switch back to emails and all works okay.

    This started happening a couple of days ago.

    10+ people found this answer helpful.
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  2. Anonymous
    2025-07-08T10:30:32+00:00

    If you deactivate the Teams Meeting-Add-In the calendar also performs normal again.

    10+ people found this answer helpful.
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  3. Anonymous
    2025-07-07T15:27:12+00:00

    The suggested resolutions did not work. Note: that this just started happening at the end of last week with no changes made to the PC. This would seem to be an Outlook calendar problem, not an access, data, or settings problem.

    10+ people found this answer helpful.
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  4. Anonymous
    2025-07-09T11:06:25+00:00

    I had the same problem, after pinning down the problem to the Teams Addin, I tried to figure out what could cause the problem.
    I checked the Version installed on my computer it was 1.25.14602 installed a few days ago.

    in the file "%localappdata%\Temp\Microsoft\Teams\meeting-addin\meeting-addin-t21-msi.log there was an error
    "IOException System.IO.IOException: The process can't access file C:\Users\Username\AppData\Local\Microsoft\TeamsMeetingAdd-in\1.25.14205\x86\Microsoft.Teams.AddinLoader.dll" because is is beeing used by another process.

    at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)

    at System.IO.FileStream.Init(String path, FileMode mode, FileAccess access, Int32 rights, Boolean useRights, FileShare share, Int32 bufferSize, FileOptions options, SECURITY_ATTRIBUTES secAttrs, String msgPath, Boolean bFromProxy, Boolean useLongPath, Boolean checkHost)

    at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share)

    at System.IO.FileInfo.Open(FileMode mode, FileAccess access, FileShare share)

    at AddinInstaller.Installer.IsFileLocked(String filePath) occurred while checking if file is locked"

    Then I downloaded the script from https://learn.microsoft.com/en-us/troubleshoot/microsoftteams/meetings/teams-meeting-add-in-missing and shut down Teams and Outlook, then ran the script as administrator (don't know if it is needed)

    Then I restarted Teams and got a new Version of the addin (1.25.18202) and now the calendar is working like before.

    8 people found this answer helpful.
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