How to Use Mac Activity Monitor to Diagnose Problems
Activity Monitor is Mac's equivalent of Windows Task Manager — and it is surprisingly powerful once you know how to use it. Here is a complete guide to diagnosing Mac problems with this built-in tool.
How to open Activity Monitor
Open Activity Monitor by going to Applications > Utilities > Activity Monitor, or search for it with Spotlight using Cmd and Space. The default view shows all running processes sorted by CPU usage. You can filter to show only your own applications by selecting My Processes from the dropdown at the top.
The CPU tab
The CPU tab shows what is using your processor. Sort by percentage CPU to see the most demanding processes at the top. A process consistently using 80 to 100% CPU when you are not doing anything demanding is abnormal. Common culprits include mds (Spotlight indexing after macOS updates), kernel_task (often indicates overheating), and browser processes.
Memory and memory pressure
The Memory tab shows RAM usage, but the most important indicator is the Memory Pressure graph at the bottom. Green means memory is plentiful. Yellow means the system is starting to compress memory — a sign you are running low. Red means macOS is actively using your drive as overflow memory. This is when slowdowns become severe.
The Energy tab
The Energy tab shows which apps are consuming the most battery power, both currently and historically. Energy Impact shows current consumption while Average Energy Impact shows the average over the last eight hours. Apps with high energy impact should be closed when you are on battery if you do not need them.
When Activity Monitor is not enough
Activity Monitor is excellent for real-time process monitoring but does not show hardware health, drive SMART status, network scanner results, or security configuration. For a complete picture — especially when diagnosing intermittent problems or checking a computer you are not familiar with — Cerebro Scan covers everything Activity Monitor misses, presented in plain English.
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