Problems · How to check
How do I check if my Mac is thermal throttling?
Three routes, in rising order of convenience. Terminal: sudo powermetrics --samplers smc,cpu_power shows package power and thermal pressure live. Activity Monitor: the CPU history window shows sustained load but not the throttle itself. Browser: a sustained load curve that slides over minutes is throttling drawn as a picture, with nothing installed and no password.
On fanless MacBook Airs, expect to find it: they step down under sustained all-core work by design, typically beginning within about five minutes. Finding throttling on an Air is confirmation, not diagnosis.
First, notice when it happens
The causes, ranked
1. Terminal: powermetrics, the real numbers
most commonHow to confirm it
Run sudo powermetrics --samplers smc,cpu_power -i 1000 during a heavy sustained load. Watch package power and any thermal pressure indication: power falling while load stays maximum is throttling in its own words.
The fix
Note the sustained package wattage after five minutes. That figure is the machine's real working budget, and it is the one that predicts export times.
2. Activity Monitor: the shape, not the cause
commonHow to confirm it
The CPU history graph shows whether load is sustained; macOS does not surface a throttle flag to it. Useful for confirming the load is real, useless for the verdict.
The fix
Use it to rule out contention (some other process was busy), then move to powermetrics or the browser curve for the throttle question.
3. The browser curve: no admin, no install
most commonHow to confirm it
A sustained test samples throughput across minutes. Flat means the Mac held its level; a slide is the settle happening in front of you; the decay percentage is its cost.
The fix
This is the route for managed Macs, borrowed Macs, and anyone who would rather not type sudo. It also produces a saved report for before-and-after comparisons.
4. Reading an Air's result correctly
commonHow to confirm it
A fanless Air that settles under sustained load is behaving to specification, not failing. The M2 Air's documented settle is roughly a quarter below peak under prolonged heavy work.
The fix
Judge it against the workload rather than against a fanned machine: bursty work barely notices, long exports do. That is the purchase question, answered after the fact.
5. When a Mac throttles more than it should
occasionalHow to confirm it
Fanned MacBook Pros settling early, or an Air far below its cohort, suggests dust, a failing fan (on Pros), or a genuinely warm environment.
The fix
Service for the fanned machines; environment and surface for all of them. Compare with the same model's published sustained behaviour before assuming a fault.
Measure it instead of guessing
The browser route is this site, and on Macs it is the one that needs no password and works on managed machines. Run the deep test, read the settle point, and save it: on Apple silicon this single number explains more about export and compile times than any peak benchmark score.
What software cannot tell you here
- No temperatures from a browser on any platform; powermetrics is the Mac route to real sensor numbers.
- We cannot distinguish design throttling from dust on a fanned Mac; that comparison needs the model's published behaviour or a service.
Asked, in people’s own words
- Do MacBook Airs throttle?
- Yes, by design: no fan means the chassis is the cooling, so sustained all-core work settles the chip down after minutes. Reviews measured roughly a quarter below peak on the M2 Air under prolonged load. Bursty work never notices; long exports always do.
- Is there an app to check Mac throttling?
- powermetrics ships with macOS and is the authoritative source; third-party menu-bar apps mostly present the same values with a subscription. For the practical question of what performance you actually keep, a sustained load curve answers more directly than any sensor number.
- How do I stop my Mac from throttling?
- On a fanned Mac: clean cooling, hard surface, cooler room, and lid open during heavy work. On a fanless Air you move the point rather than remove it, because the design chose silence over sustained power. Frame the goal as settling higher, not never settling.