This guide helps you identify and resolve high CPU usage issues on macOS Tahoe—commonly caused by misbehaving apps, system processes, or resource-heavy background tasks.

1. Identify the culprit

  1. Open Activity Monitor (Spotlight > Activity Monitor).
  2. Go to the CPU tab and sort by % CPU.
  3. Note the top process—if it’s a regular app, that’s the likely offender; kernel_task or WindowServer are system processes.

2. Fix common causes

  • App updates—check in the App Store or app’s menu
  • Login items—disable from System Settings > General > Login Items
  • kernel_task—cool down the Mac, disconnect peripherals, or reboot
  • WindowServer—close extra windows, turn off transparency (System Settings > Accessibility > Display)
  • Spotlight—let indexing finish or re-index:
    sudo mdutil -E /

3. Clean up routine

  • Run a clean-up tool like CleanMyMac or run:
    sudo periodic daily
    to clear caches
  • Monitor CPU in Activity Monitor; if spikes persist, consider reinstalling the offending app or resetting the NVRAM:
    Command + Option + P + R

4. Checklist

  • Update macOS and apps
  • Remove unnecessary login items
  • Reboot (or safe mode) after changes
  • Run a system cleanup
  • Re-monitor CPU