Load average

Open Terminal and run uptime. The last three numbers are the 1, 5, and 15 minute load averages. You can also run sysctl -n vm.loadavg.

To compare it with your core count, run sysctl -n hw.logicalcpu.

If the 1 minute number is much higher than the 15 minute number, load is rising. If it is lower, load is falling. A load that stays well above your core count for a long time means work is waiting for the CPU, and the Mac will feel slower.

The two measure different things. % CPU and the Idle figure show how much of the time the cores were busy. Load average, as the top manual puts it, is the average number of jobs in the run queue: threads that are running or ready to run.

That is why they can disagree. Your Mac can show plenty of Idle in Activity Monitor while the load average is above your core count. Many short tasks can pile up in the queue without keeping every core busy for the whole interval.

To compare the two, divide the load average by your core count from sysctl -n hw.logicalcpu. A result below 1 means, on average, every thread that wanted a core could get one.

uptime prints the three numbers once. To watch them change, run top in Terminal. The line near the top that starts with Load Avg shows the 1, 5 and 15 minute values, and the CPU usage line below it shows user, sys and idle percentages, so you can see both at the same time. Press q to exit.

For a single snapshot you can paste into a note or a script, run top -l 1 -n 0 | grep "Load Avg".

A high load is a symptom, not a fault. Read it together with how the Mac feels.

• It matters when the load stays well above your core count and apps respond slowly, since work is waiting for a turn on the CPU.
• It matters less during a build, an export or a big copy. Those jobs are supposed to fill every core.
• On Apple silicon, the core count includes efficiency cores. macOS runs a lot of background work on them, so a load near your core count can still leave the performance cores free for the app you are using.
• A load that rises for no clear reason and stays up usually has a busy process behind it. Find it before you worry about the number.

1. In Activity Monitor, click the CPU tab and sort by % CPU to find processes doing the most work.
2. In Terminal, run top -o th -stats pid,command,cpu,th. The #TH column shows total threads and, after the slash, how many are running right now.
3. Processes with several running threads are the ones adding the most to the load. Quit what you do not need and check the load again after a few minutes, since the 1 minute value reacts first.