Why is my Mac hot after an update?

After a big macOS update, your Mac has catching up to do in the background. That work makes heat, and it usually fades on its own. Here's how to tell, and what to do if it doesn't.

5 min read ·

Your Mac is catching up

A major macOS update changes a lot under the hood, and afterwards your Mac often redoes work it had already finished:

  • Spotlight rebuilds its search index, so search keeps finding your files, mail and messages.
  • Photos may analyze your library again, recognizing faces, places and objects.
  • iCloud and other sync services check that everything still matches.

On a Mac with years of photos and mail, this can keep the chip busy for hours, sometimes a day or two. During that time it's warmer than usual and the battery drains faster. It's normal, and it ends by itself.

Check that it's the catch-up

  1. Open Activity Monitor (Command-Space, then type its name) and click CPU.
  2. Sort by % CPU and look at the names near the top.

Names that mean background catch-up include mds, mds_stores and mdworker (Spotlight indexing), and photoanalysisd or mediaanalysisd (Photos analysis). Seeing them high for a while after an update is expected.

Help it finish sooner

  • Plug it in and let it run. Leave the Mac awake and on power for a few hours, for example in the evening, on a hard surface. Background work generally goes faster when the Mac isn't saving battery.
  • Don't keep restarting. One restart is fine, but the work has to finish at some point.
  • Update your apps. After a big macOS update, an app that hasn't been updated yet can misbehave. Check the App Store and each app's own updates.

When it isn't the update

If your Mac is still hot after a few days, look again:

  • One app stays high in Activity Monitor. Update it, or quit it and see whether the heat goes. Check its maker's site for a fix for the new macOS.
  • Spotlight never seems to finish. Apple's steps to rebuild the index: open System Settings, click Spotlight (or Siri & Spotlight), click Search Privacy (or Spotlight Privacy), add your disk with +, wait a few seconds, select it and remove it with –, then click Done. Spotlight then indexes that disk again from the start, so expect another round of background work.
  • Nothing looks busy, but it's still hot. See why a Mac runs hot for the full checklist, and contact Apple if it persists.

Sources

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