One thing to check is your cached profile you can turn down the amount off data being stored on the computer to save space and help speed up the the loading process. Below is a guide:

Turn Cached Exchange Mode on or off

  1. Click File > Account Settings > Account Settings.
    Account Settings in the Backstage view
  2. Click the Exchange or Microsoft 365, and then click Change.
    Change command in the Account Settings dialog box
  3. Under Offline Settings, check Use Cached Exchange Mode.
    Use Cached Exchange Mode check box in the Change Account dialog box(If you're a Microssoft 365 subscriber with semi-annual updates, under Offline Settings, check Use Cached Exchange Mode to download email to an Outlook data file.
Account setup dialog, Exchange Account Settings page.


4. Turn down the slider to 6 months or 3 month



This will decrease the amount of older data stored on your ocmputer but should you need to you can still access this using office.com and using the web version of Outlook or using the search function which will prompt a server search.