How the instruments measure

Event sources

Every instrument reads standard browser events and nothing else. The polling-rate instrument prefers pointerrawupdate, which fires for every report the OS delivers; it falls back to coalesced pointermove events and, as a last resort, to plain pointermove, which is limited to one event per frame and gets no verdict. Buttons are read from the buttons bitmask; keys from KeyboardEvent.code.

Clock precision

The site is served with cross-origin isolation (COOP and COEP), which gives timers a 5 µs step in Chromium instead of 100 µs. Event timestamps may still be coarser, so each instrument measures the actual step from the data and shows it in its header. A step of 1 ms or more turns rate measurements into estimates.

Verdicts

Every instrument returns one of four grades: pass, marginal, fault, or cannot measure here. The thresholds are listed on each instrument page, together with what the browser cannot measure.

Version

Algorithm version 1, October 2026.