CPU Performance Test

What a browser benchmark can honestly tell you

This is worth saying plainly, because most online benchmarks do not. A web page cannot measure your hardware. It can only measure how fast this browser, on this machine, right now gets through a particular piece of work — and a great deal sits between that and your components.

• The browser's JavaScript engine is doing the work, and different browsers produce different numbers on the same machine.
• Other tabs and applications compete for the same cores. A background video call can halve a score.
• Thermal and power state matter. A laptop on battery, or one that has been working hard, throttles. The same machine can score forty per cent lower ten minutes later.
• The browser deliberately hides things. Core count is rounded, memory is capped at 8 GB regardless of what is installed, and graphics details are masked in some browsers.

So treat the score as a rough, relative figure: useful for comparing two browsers on one machine, or the same machine before and after a change. Not useful for comparing your computer to someone else's, and no substitute for a native benchmark.

Run it more than once

The first run is usually the slowest, because the JavaScript engine has not yet optimised the code it is about to run repeatedly. Run it three times and take the best.

What the three tests do

• Integer work — a tight arithmetic loop. This is the closest thing here to raw single-core throughput, and it is the most stable of the three.
• Floating point — square roots and logarithms, which lean on different silicon and on the engine's maths library.
• String building — allocating and joining many small strings. This exercises memory allocation and garbage collection as much as the processor, and it is the test most affected by what else the machine is doing.

All three are single-threaded. A sixteen-core processor scores much the same as a four-core one here, because the test uses one core either way. That is a limitation of the test rather than a finding about your machine.

How to use it

1. Close other tabs and applications first. This matters more than anything else you can control.
2. Plug the laptop in if it is on battery. Power saving changes the result substantially.
3. Press run and leave the tab in the foreground — browsers throttle background tabs.
4. Run it three times and use the best. The first run is always the slowest.

Common uses and tips

• Comparing browsers on the same machine, which is the one comparison this measures fairly.
• Checking whether something is throttling — run it, then run it again after ten minutes of load and see how far the number falls.
• Before and after a change, such as disabling an extension or changing a power setting.
• Not for comparing computers. Too much sits between the score and the silicon.

Questions people ask

Does this measure my actual CPU?

Not directly. It measures how fast this browser gets through a JavaScript workload on this machine, which is affected by the browser, other applications, and thermal throttling.

Why does my sixteen-core processor not score higher?

Because the test is single-threaded. Extra cores make no difference to it.

Why is the score different every time?

Background activity, thermal state and JavaScript engine warm-up all move it. The first run is usually the slowest.

Why does another browser give a different number?

Different JavaScript engines optimise differently. Comparing browsers on one machine is the fairest use of this test.