Beacon guide

See which processes are using the most CPU on Mac

How to quickly find the process eating your CPU — whether it's a runaway browser tab, a stuck app, or something you didn't even know was running.

4 min read

Your laptop is hot, the fans are loud, and you’d bet money something is hammering the CPU — but you don’t know what. The hard part isn’t fixing it; it’s finding it. Once you know the process, killing it (or quitting the app it belongs to) is usually trivial.

Here’s how to actually find it.

Two paths

The native way (Activity Monitor or top)

Open Activity Monitor, go to the CPU tab, click the % CPU column header to sort descending. Watch for 30 seconds — the process that consistently sits at the top is your culprit. A short spike is normal; sustained 80%+ is not.

From Terminal, top -o cpu gives you the same thing without leaving your shell. Or top -o cpu -stats pid,command,cpu,cpu_me,cpu_others -l 5 for five samples with custom columns. ps aux | sort -nrk 3 | head -10 is the quick one-shot version.

This works fine. The only real downside: you have to actively go look. By the time you notice the heat and switch to Activity Monitor, the offending process sometimes calms down — and now you have no idea what just happened.

The Beacon way

Beacon’s menu bar panel keeps a live top-processes list one click away, plus history so you can see what was running 30 seconds ago.

  1. Install Beacon so it lives in your menu bar.
  2. Click the Beacon icon to open the panel.
  3. Look at the Top Processes section — it's sorted by CPU and updates every second.
  4. To kill a runaway process, click it and choose Quit (or Force Quit if it's truly stuck).
  5. Scroll the small CPU history chart at the top to see the spike, then look at what was active during it.

Two things worth knowing. First: a process showing 200% CPU isn’t a bug — it’s using two full cores. Modern Apple Silicon Macs have 8 to 16 cores, so total CPU can go well past 100%. Second: WindowServer high in the list usually means a misbehaving GPU-heavy app (often a browser tab with too much animation). Quitting the tab, not WindowServer, is the fix.

The combination of always-visible total CPU plus a one-click top-process list is the bit that saves time over plain Activity Monitor.

← All Beacon tips