Office applications have been running slow especially since my mailbox has been migrated to Office 365. What can be done to fix this?

Here are a list of things to try to help with the performance of OfficeWord, Excel, Outlook. Please try them one at a time to determine if your issue is resolved before trying the next one.

Before making any changes to your computer you may want to contact you local IT support to see what they recommend or to have them do the work.


Quick and Easy:

  1. Confirm thatOutlook is running in "cache mode"
  2. Limit the number of Calendars in the "My Calendars" folder. When calendars are listed here they are synchronizing regulatory while Outlook is open.
  3. Troubleshooting tip: Check the connection status for Outlook. This can be done by holding Ctrl key and right-clicking the Outlook quick-launch icon in the system tray near the clock. Select connection status. The number of persistent connections utilized by Outlook will be displayed. Connection latency can be spot checked by clicking the reconnect button and observing the connection time. If a user has numerous calendars in their “My Calendars” folder, you will see those additional connections listed here.
  4. Limiting the number of items in the Inbox, the Deleted Items, and Sent Items folder to under 5,000 will improve client performance.


More complex things to try:

  1. Outlook Add-Ins that are not needed should be disabled, especially iCloud. Click here to learn how to manage these.
  2. "Disable Graphics Acceleration" is a feature that is not compatiblewith all graphic cards andmay cause performance issue. To disable: File -> Options -> Advanced -> Display and check the box for "Disable Graphics Acceleration"


Proceed with caution when trying these:

  1. Microsoft Office Configuration Analyzer Tool can help identify any known configuration issues that could be causing issue.
  2. Create a new Outlook Mail Profile causing a new Outlook Data File (.ost) to be created.


Created: Aug 22, 2017 - 8:4am Updated: Feb 11, 2019 - 9:30am Author: UIT Support Center Article: 2834
Was this article helpful?

Thank you for your feedback. Click Here to submit again.