Outlook gets sluggish as mailbox grows
Past a few hundred thousand items in a folder, Outlook feels it. Cache, OST size and search index all play a part.
Try this first
- 1Check OST file size; over 50 GB you notice slowdown
- 2Lower cache period in account settings to 6 or 12 months
- 3Split huge folders and archive older items
- 4Rebuild the search index if search is also slow
When to bring us in
If lowering cache and archiving does not help, or OST keeps corrupting.
See also
- Outlook crashes or freezes on large attachmentsUsually the mailbox cache is the culprit, not Outlook itself. Shrinking or relocating usually helps within ten minutes.
- Teams: they cannot hear me, or I hear nothingIn our experience Teams usually picked the wrong audio device after a Windows update or a new headset.
- OneDrive has stopped syncingThe cloud icon is grey or has a warning. Locally changed files are not showing up for colleagues.
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