What this measures
Half the time is Array.sort on 12,000 numbers. The other half is a counting sort on small integers. The two rates are different jobs, so a higher counting-sort number is not a win.
How to read it
Read the raw rate first. The index, when it appears, is only the integer rate divided by a fixed 40 million operations per second. Compare two runs of the same page, on the same browser, with the same duration.
What it cannot do
A web page cannot name the processor, read temperature, set the clock, or prove a core is faulty. Workers may be fewer than the cores you paid for. Do not treat the index as a rank.
Questions
Does this show my CPU model?
No. The browser does not pass the brand or the clock. The logical processor count is the only hardware-shaped number, and it can be reduced.
Why does multi-core not scale?
Workers share power, heat, and memory bandwidth. The browser may also offer fewer workers than the chip has cores.
Can the stress test damage the PC?
It is a short, capped JavaScript loop with a stop button. It cannot command fans. Stop it if the device feels too hot.