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QUEST · LV.07

CPU test (quick stress & score)

Load every CPU thread for a short time, get a score, and see whether performance drops as it heats up.

Runs in your browser · Nothing uploadedFree · No install

CPU test (quick stress & score)

Short, browser-based load test

This puts your computer under heavy load for up to 60 seconds. Fans may spin up and the device will get warm — that’s normal. It stops automatically, when you press Stop, or when you leave the tab. Lighter than dedicated tools like Prime95 or FurMark.

Ready. Results appear here.

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CPU threads
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Single-core score
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Multi-core score
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Score = millions of test operations per second. Compare on the same browser — different browsers run JavaScript at different speeds.

Result

Not tested

Waiting for you to start the test.

How to use

  1. 1Close heavy apps, plug in your laptop, then choose a duration.
  2. 2Press Start. A single-thread phase runs first, then all threads.
  3. 3Compare the score and check the throttling result.

Troubleshooting guide

The FreeComTools mascot checking a CPU on a motherboard with a stethoscope

What this CPU test does

The test runs a fixed integer-and-floating-point workload in background threads (Web Workers). First it measures one thread for a few seconds, then it starts one worker per logical CPU thread and keeps them busy for the duration you chose. You get a single-core score, a multi-core score, how well performance scales across cores, and whether speed dropped towards the end.

It is a quick health check, not a replacement for dedicated stress tools. Browsers limit how hard a web page can push your hardware, so expect less heat than Prime95, Cinebench or OCCT.

Reading the results

  • Single-core score: how fast one thread is. Matters for everyday responsiveness, browsers and many games.
  • Multi-core score: total throughput with every thread working. Matters for video export, compiling and rendering.
  • Multi-core scaling: multi-core ÷ single-core. On a healthy CPU this is roughly the number of performance cores plus some extra for hyper-threading and efficiency cores.
  • Slowdown at the end: how much slower the last quarter was than the first. Over 20 % usually means thermal or power throttling.

Throttling? Check these

  1. Laptops: plug in the charger and choose “Best performance” (Windows) or turn off Low Power Mode (macOS).
  2. Clean dust from vents and fans; use the laptop on a hard surface, not a bed or sofa.
  3. Desktops: check that the CPU cooler fan spins and that case fans move air in and out.
  4. If the PC is several years old, renewing the thermal paste between the CPU and cooler often lowers temperatures a lot.
  5. Close background apps — antivirus scans and updates can steal CPU time during the test.

Why the score differs between browsers

Chrome, Edge, Firefox and Safari use different JavaScript engines, so the same computer scores differently in each. For a fair comparison (before/after cleaning, or two computers), use the same browser and close other tabs.

Safety

The test is capped at 60 seconds, stops automatically when you switch tabs, and can be stopped any time. Modern CPUs protect themselves by slowing down if they get too hot, so a short test like this cannot damage a working computer.

Frequently asked questions

Can a browser CPU test damage my computer?

No. It is short, capped at 60 seconds, and CPUs automatically slow down to protect themselves from heat. If your PC shuts down during a short test, the cooling or power supply needs attention anyway.

Why does it show fewer cores than my CPU has?

Browsers report logical threads, and some (like Safari) may limit the number reported for privacy. The test uses as many threads as the browser exposes.

Can I see CPU temperature?

No — browsers can’t read temperature sensors. Use tools like HWiNFO (Windows) or your laptop manufacturer’s app while running the test.

What is a good score?

It depends on the browser and CPU. Use it to compare the same computer over time (for example before and after cleaning) or two computers in the same browser.

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