macOS · Troubleshooting
Diagnose CPU, Memory & Energy Problems
Activity Monitor is macOS's built-in tool for seeing exactly what's using your Mac's CPU, memory, energy, disk, and network resources in real time, broken down by individual app and process. It's the first place to look when the Mac feels slow, hot, or the fan is running loudly.
How to open Activity Monitor
- Open Activity Monitor (Applications → Utilities → Activity Monitor, or search with Spotlight).
- Click the CPU, Memory, Energy, Disk, or Network tab depending on the symptom.
- Click the column header (like '% CPU') to sort and find the top resource user.
- Select the problem process and click the Stop (X) button to force it to quit if needed.
What you should know
- Shows live CPU, Memory, Energy, Disk, and Network usage tabs, each sortable by app.
- Lets you force-quit an unresponsive or runaway app directly from the toolbar.
- Displays which apps are consuming the most energy, useful for diagnosing battery drain.
- Includes a floating Dock icon graph option for at-a-glance CPU or network monitoring.
Why it matters
Activity Monitor turns a vague 'my Mac feels slow' complaint into a specific, actionable diagnosis by showing exactly which app or process is responsible. It's essential for catching runaway processes, battery-draining apps, or memory leaks before they cause a crash or force a restart.
Best practices
- Check the Memory tab's 'Memory Pressure' graph, not just app RAM usage, to judge real memory strain.
- Sort by Energy Impact when troubleshooting unexpectedly fast battery drain on a MacBook.
- Quit and reopen a specific app that's misbehaving before force-quitting through Activity Monitor as a last resort.
Common problems and fixes
- An app is unresponsive and won't quit normally.
- Select it in Activity Monitor's Process list and click the Stop button, then choose 'Force Quit' to close it immediately.
- CPU usage stays high even after closing visible apps.
- Check the full process list for background helper processes or system services using excessive CPU, and restart the Mac if usage doesn't settle after investigating.
Tips and tricks
- Go to View → Dock Icon in Activity Monitor to show a live CPU or network graph directly in the Dock for constant monitoring.
Frequently asked questions
Is it safe to force-quit any process I don't recognize?
No — many unfamiliar-looking process names are legitimate system services; only force-quit processes tied to a specific app you know is misbehaving.
What does 'Memory Pressure' actually mean?
It's a graph showing how hard macOS is working to manage available memory; green means comfortable, yellow means memory is getting tight, and red means the Mac is under significant memory strain.
Related settings
- Storage ManagementStorage settings show a visual breakdown of exactly what's using space on your Mac's disk, plus built-in recommendations — like storing files in iCloud or automatically emptying the Trash — to free up space without manually hunting for large files yourself.
- Login Items & ExtensionsLogin Items & Extensions settings control which apps and documents open automatically when you log in, plus which system extensions — like Finder add-ons, sharing options, and background helper processes — are allowed to run.
- Safe ModeSafe Mode starts your Mac with only essential system software and drivers loaded, skipping login items, most fonts, and system caches. It's a diagnostic first step used to determine whether a startup problem is caused by third-party software or a deeper system issue.
More Troubleshooting guides for macOS
- Erase & Reset MacErase All Content and Settings lets you wipe your Mac back to factory defaults — useful for major troubleshooting, or before selling, trading in, or giving away your device.
- macOS RecoverymacOS Recovery is a built-in set of utilities for reinstalling macOS, restoring from a Time Machine backup, repairing a damaged disk, and resetting a forgotten password — all accessible without needing a working copy of macOS already running.
- Analytics & ImprovementsAnalytics & Improvements controls whether your Mac automatically sends crash reports and usage analytics to Apple, and optionally to third-party app developers, to help them find and fix bugs. It's separate from location services and general privacy settings, focused specifically on diagnostic and usage data.
- Disk Utility First AidRun Disk Utility's First Aid tool to check a disk or volume for directory and file system errors and attempt automatic repair.
- Apple DiagnosticsUse Apple Diagnostics, launched at startup, to test your Mac's hardware components including memory, logic board, and battery for underlying issues.
- Console: View System LogsUse the Console app to view real-time and historical system logs, crash reports, and diagnostic messages generated by macOS and installed apps.