CPU Test
Run a quick speed test on one core, then on all of them.
Threads reported by the browser; privacy settings can lower this number.
Ready.
Every test runs inside your browser. Nothing you type, say, show or press is uploaded.
How to use this test
The CPU test runs a fixed workload of math, sorting and hashing in your browser, first on one thread and then on all threads at once, and turns each run into a score. It also shows how many threads your browser reports and has a stress test that keeps every thread busy so you can see whether the speed drops.
Close heavy tabs and plug in your laptop. Press Single-core and wait three seconds, then press Multi-core. For the stress test, choose 30, 60 or 120 seconds, press Start stress test and watch the line: flat means the CPU holds its speed, falling means it is slowing down to stay cool.
What the results mean
Scores only compare fairly in the same browser, because each browser runs JavaScript at a different speed. Divide the multi-core score by the single-core score to see how well the work spreads across threads. A drop of more than a few percent from the start to the end of the stress test usually means heat or power limits, which are common on thin laptops and on battery.
Common questions
Why does it show fewer threads than my CPU has?
Some browsers limit the number for privacy. Safari reports 4 or 8 whatever your processor has, and Firefox with fingerprinting protection on reports a fixed number. Chrome and Edge report your logical processors, the number of threads your CPU can run at once.
Can this test damage my CPU?
No. It's the same kind of load as a game or a video export, and processors slow themselves down if they get too hot. You can stop the test at any time.
Why is my laptop slower on battery?
Laptops cut processor power on battery to save energy. Plug in and choose the best performance power mode to see the full speed.