Diagnose
Start from the symptom, end with the cause.
The things people type into a search box, each answered by a measurement and an honest note on what a browser cannot see.
Find your symptom, then measure it
Pick the symptom closest to yours from the 10 below. Each page explains what the free 3-minute browser stress test shows for that problem, which curve shapes to look for, and what the test cannot see, so you can tell a machine meeting a heat or power limit from one that is busy, misconfigured or simply slow, before you spend money on it.
Every symptom page points the same way: run the test, read the shape, then check the cause the shape is consistent with. For the causes themselves, the fix articles rank them by likelihood with a check and a fix for each, the guide to thermal throttling explains the most common one in depth, and the glossary defines terms such as sustained clock and power limit that the report uses.
A slow PC is a symptom, and the same symptom has several possible causes. A machine that feels fine for two minutes and sluggish by the fifth is usually meeting a heat or power limit. One that is slow from the first second is more often short of memory, drawing on the wrong graphics chip, or busy with something in the background. Guessing between those from how it feels is how people end up buying hardware they did not need.
Each page below starts from one thing people actually type into a search box and answers it with a measurement rather than a checklist. The free browser test loads your processor, memory and graphics for three minutes, records what they deliver the whole way through, and reports the shape of that curve: held steady, stepped down once, slid gradually, or swung about.
Every page also says what the browser cannot see. There is no temperature reading, no fan speed and no wattage, because no browser exposes them. Where a cause is inferred from the shape of a curve, it is named as an inference and carries a confidence, rather than being presented as a sensor reading.
Good places to start
- Checking a refurbished laptopIt arrived. It looks fine. You have fourteen days to find out.
- Video calls stutterThe connection is fine. The call still falls apart.
- It freezes under loadIt does not slow down. It stops.
- PC slows down after a few minutesFast, then slow. That is a curve, and a curve has a cause.
- Laptop overheatingHot to the touch. Here is what the heat is costing.
- CPU throttling testA throttling test that names the kind. Power limit or heat, not just a percentage.
- FPS drops over timeSixty frames, then forty. The counter says what. The curve says why.
- Laptop slow on batteryUnplugged, and half the machine. Measure the gap instead of guessing it.
- New PC underperformingThe parts are right. The machine is not.
- Is my PC throttling?Is it throttling? Yes or no, then how much, then why.
Questions
A machine that is quick at first and slower later is most often meeting a heat or power limit, but background work and power settings can feel the same. The test records throughput the whole way through and names the shape of the curve; the shape is consistent with some causes and not others, and a sensor tool confirms which.
Not directly. No browser can read a temperature. It shows whether throughput falls away over the run and how, and says when that shape is consistent with heat, with a power limit, or with something else.
The standard run takes 3 minutes. The deep run takes 9 minutes and adds a hot re-test against the cold run, which helps with symptoms that only appear once the machine is warm.
No. The test runs in the browser. Installing a sensor tool afterwards is the way to confirm a cause the curve points to.