When Microsoft apps on iPhone (Outlook, Teams, OneDrive, Microsoft 365) get slow, it’s usually a mix of storage pressure, background limits, or a stuck sync/cache. The good news: you can often get speed back in under 15 minutes.
Start with the quickest checks first, then move down the list.
1. Force close the Microsoft app and restart your iPhone
If the app has been open for days, a small memory or sync hiccup can snowball into lag.
- Swipe up from the bottom (or double-press Home) and swipe the app away.
- Restart iPhone: hold Side + Volume button → slide to power off → turn back on.
- Open the app again and give it 30–60 seconds to settle.
It sounds basic, but it fixes a surprising amount of “suddenly slow” behavior.
2. Check iPhone storage (low storage causes system-wide slowdown)
When iOS is short on free space, apps can take longer to open, search, download attachments, and cache content.
- Go to Settings → General → iPhone Storage.
- Aim for at least 2–5 GB free (more is better if you handle lots of files).
- If you’re tight: remove offline downloads, large videos, or unused apps.
If OneDrive is set to keep a lot of files offline, storage pressure can show up as “everything feels laggy.”
3. Update the Microsoft app (and iOS) to clear performance bugs
Microsoft apps update frequently, and performance regressions do happen—updates are often the fix.
- Open App Store → your profile icon → update Outlook/Teams/OneDrive/Microsoft 365.
- Then check iOS: Settings → General → Software Update.
If your iPhone is on a much older iOS version, newer Microsoft app builds may struggle more than expected.
4. Clear or reduce heavy caches/offline data (especially OneDrive and Teams)
Large caches and offline files can slow search, scrolling, and load times—particularly after big sync cycles.
- OneDrive: remove unneeded offline files (mark as online-only where possible).
- Teams: if chats/files are sluggish, a reinstall often clears bloated local data (see step 6).
- Outlook: reduce the amount of mail stored offline if the app offers the option (varies by version/account type).
If the slowdown started right after a big folder sync or large attachment download, this step matters a lot.
5. Disable Low Power Mode and allow background refresh (when you need speed)
iOS can throttle background work and network activity. That can make Microsoft apps feel like they’re “catching up” every time you open them.
- Turn off Low Power Mode: Settings → Battery → Low Power Mode.
- Check Background App Refresh: Settings → General → Background App Refresh (Wi‑Fi or Wi‑Fi & Cellular).
- Make sure the specific Microsoft app is allowed.
If you prefer to keep Low Power Mode on, expect slower sync and more “loading” moments—especially in Teams and Outlook.
6. Reinstall the app (best for persistent lag, crashes, or stuck sync)
If a Microsoft app is consistently slow even after updates and storage fixes, reinstalling can remove corrupted local data and reset the app’s cache.
- Confirm you know your sign-in method (password + MFA, Authenticator, etc.).
- Delete the app → restart iPhone → reinstall from the App Store.
- Sign in and let it sync on Wi‑Fi for a few minutes before judging performance.
Tip: If you manage work accounts, your organization’s policies may reapply settings after sign-in—give it a moment.
Final thoughts
On iPhone, Microsoft app slowness is most often caused by low storage, aggressive power saving, or an app cache/sync that needs a clean restart.
If you try all six and it’s still slow, test on a different network (Wi‑Fi vs cellular) and note whether the lag is only with attachments, search, or sign-in—those clues narrow the next fix fast.