My Mac is 4 years in, slow, full and weird. Someone said 'just reset'. When is that the right call?

macOS is more robust against rot than Windows, so a full reset is rarely the first step. But with accumulated junk, a corrupt user profile or a handed-down Mac, it's sometimes the cleanest option.

Try this first

1. 1Lighter first: open Activity Monitor, sort by CPU and Energy. A specific process at 50 percent CPU isn't reset-material, that's targeted fixing. Often a sync tool, an AV component, or Spotlight.
2. 2Try safe mode (boot holding Shift on Intel, or hold power on Apple Silicon and pick 'Continue in Safe Mode'). If safe mode is fast, the cause is a login item or kernel extension, not macOS.
3. 3If only one user is slow, create a test account and sign in. Fine = user profile corrupt. Migrate documents to a new account, takes 30 minutes.
4. 4Reset is appropriate when: 1) you're handing the Mac off or selling, 2) you suspect malware remnants, 3) after an upgrade chain of 4+ macOS versions with no clean install in between.
5. 5Take a Time Machine backup or manual copy of Documents, Desktop, Photos library first. Then System Settings, General, Transfer or Reset, 'Erase All Content and Settings'. Works on T2 or Apple Silicon Macs (almost all Macs since 2018).
6. 6After reset: don't immediately restore from Time Machine (you'll bring back the old junk), set up as new and copy actual data manually. Time-consuming, but that's the point.

None of the above fits?

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