Your Mac is slow after a macOS update: what's going on and what to do

Why it happens

After an update, Spotlight, Photos and iCloud rebuild their indexes in the background. Spotlight re-reads your files so search works, and Photos re-scans your library for faces and objects. That work can take hours or days on a big drive or photo library, and the Mac feels slow and warm until it's done.

How to fix it

1. Plug in the charger and keep the Mac awake for a day or two. Background indexing pauses while the Mac sleeps, so leaving it on lets it finish sooner.

2. To see what's busy, press Command-Space, type Activity Monitor and press Return. Click CPU, then the % CPU column heading.

   Activity Monitor›CPU

3. Look for mds_stores or mdworker (that's Spotlight) and photoanalysisd (that's Photos). If they're near the top, it's normal catch-up work. Leave them running; they slow down by themselves when they finish.

4. For Photos, quit the Photos app while it catches up. Analysis runs fastest when the Mac is idle and plugged in.

5. After a day or two, restart once from the Apple menu. If it's still slow after that, work through the steps below.

Still not fixed?

1. Update your apps too. An older app or plug-in that doesn't fully support the new macOS can keep working hard in the background. Check the App Store and each app's own updates.

2. Install any follow-up update in General > Software Update. Apple often fixes early problems in the first point release.

   General›Software Update

3. If Spotlight is still busy after several days, rebuild its index: add Macintosh HD in Search Privacy…, wait a few seconds, then remove it.

   Spotlight›Search Privacy…

4. Remove apps you don't need from Open at Login, and check your free space in Storage. A nearly full drive makes everything slower.

   General›Login Items & Extensions›Open at Login

5. If your Mac is still slow a week later with nothing busy in Activity Monitor, start in Safe Mode to test. If it's slow there too, contact Apple Support.