Open Activity Monitor and quit heavy apps, keep at least 10–15% storage free (System Settings → General → Storage), remove unnecessary Login Items, update macOS and apps, and restart. Avoid “cleaner” apps.

The short explanation

macOS needs free space for swap and caches. Low storage slows everything. After updates or migrations, Spotlight and Photos indexing can make a Mac sluggish for a day.

Symptoms

  • Spinning beach ball.
  • Slow app launches.
  • Fans loud and Mac hot.

What causes it

  • Low free storage.
  • Heavy apps/tabs and extensions.
  • Many login items and background apps.
  • Indexing after updates; old hardware.

Try these fixes

  1. Check Activity MonitorSort CPU and Memory; quit runaway processes. Check Memory Pressure.
  2. Free storageSystem Settings → General → Storage; follow recommendations.
  3. Login itemsSystem Settings → General → Login Items & Extensions; remove unneeded ones.
  4. UpdateInstall macOS and app updates.
  5. Browser hygieneClose tabs and remove heavy extensions.
  6. RestartRestart weekly to clear memory and swap.
How to tell it worked: Apps open promptly and Memory Pressure stays green.

Avoiding it in future

Keep storage free and limit startup apps.