Recovery. Does it come back after a break?
The CPU stage's own workload, run twice with 45 seconds of nothing between: a machine that recovers its speed after idling reads near 100%, and one that stays throttled reads below it.
An illustration of the shape, not a measurement. The test reports your own figures.
Load
Every core, 15 s
Idle
45 s, nothing running
Burst
Every core, 15 s
Duration
75 seconds
Run it
The recovery test. 75 seconds, in this tab.
15 seconds of load, 45 idle, 15 of load. Keep this tab in front.
What you will get
Whether your processor comes back at its warm speed after a short break, how many seconds the burst takes to settle, and the noise floor the answer is read against. Nothing is uploaded.
Load, rest, load again.
A stress test says how much speed a machine loses under load. This test asks the next question: once the load stops, does the speed come back? A power limit that resets on idle does; a machine that is still hot, or that a firmware has clamped, does not.
- The warm reference
- Every logical core runs the CPU stage's workload for 15 seconds, long enough for a short power budget to expire on most laptops. The last 5 seconds are the warm reference: what the machine gives once it has been working.
- The break
- 45 seconds of nothing. The workers are gone, the page draws only a countdown, and the clock pauses if the tab is hidden. 45 seconds is our choice and it is shorter than a real break; a machine that needs longer to cool reads as not recovered here, which is a true statement about 45 seconds.
- The burst
- The same load again for 15 seconds. Its first 5 seconds are compared with the warm reference; its last 5 seconds are its own settled level.
- The same workload as the run
- The load is the CPU stage's code, imported rather than copied, so a figure here is in the same units as the stage's and cannot drift from it.
Three numbers, and the noise they sit in.
No score. The result is a percentage, a time and the noise floor, and words for what they mean.
Recovery
The burst's first 5-second mean over the reference's last 5-second mean, as a percentage. 100 means the machine came back at its warm level. Above 100 means the break let it run faster than it had been running warm, which is what a reset power budget looks like. Below 70 reads as held back.
Time to settle
Seconds into the burst at which a one-second bin first reached 95% of the burst's final level. Reported only when that final level held still; a burst still sliding in its last 5 seconds has no level to reach and the result says so.
Noise floor
The reference's sample-to-sample jitter after its warm-up, as a share of its mean. A recovery gap smaller than two and a half times this figure is reported as within noise, and the verdict is recovered.
Flags
If workers could not start and the load ran on one thread, the result is marked as a fallback and is not comparable. If the tab was hidden for more than a second, the clock paused but the machine kept cooling, and the result says the break was longer than intended.
An illustration of the shape, not a measurement. The test reports your own figures.
Hardware
What it needs. Three tiers, no fine print.
Minimum
Any recent browser
Chrome, Edge, Firefox or Safari on a laptop or desktop. Web Workers are needed for a multi-core load.
Recommended
Plugged in, other apps closed
On battery a laptop's power limits change the reference and the burst alike, and a background program on the cores changes both.
Optimal
Run it after the stress test
A machine that has just finished the stress test is warm; this test then says whether 45 seconds is enough to get its speed back.
Questions
Recovery, answered
- What does a recovery test measure?
- Whether a processor gets its speed back after it stops working. Every core is loaded for 15 seconds, left alone for 45, then loaded again. The burst's first 5 seconds are compared with the reference's last 5: near 100% means the machine recovered, and well below it means whatever slowed it down had not cleared.
- Why does my result read above 100%?
- Many laptops allow extra power for the first seconds of a load, then settle to a lower limit. If the break resets that budget, the burst starts at the higher level and reads above the warm reference. That is the power budget resetting, and it is the normal shape on a well-cooled machine.
- Why only 45 seconds of idle?
- Because the test has to end. A real break between sessions is minutes; 45 seconds is long enough for a power budget to reset and short enough to sit through. A machine that stays held back after 45 seconds is one whose heat, or whose firmware, needs longer than that, and the result says so rather than guessing at a longer break.
- Is this part of the main SystemCheck run?
- No. It runs on this page only, on its own, and it does not change the score or the report. The Deep run's hot re-test asks a related question over a longer time.
- Why does it not show temperature?
- No browser can read a temperature sensor. The test measures the effect, lost or recovered speed, which is what you would notice.