Performance

Values may refresh about 1 000 times per second, so functions used at each refresh must be cheap: no allocation in hot paths, precomputed tables, formatter objects cached. Every optimisation is measured against a naive baseline in benchmarks/ (pnpm bench), in Chromium through Playwright: the functions run where they run in the applications, with precise timers (the page is cross-origin isolated).

Operation	Library	Baseline	Gain
roundToFractionDigits	arithmetic	Number(formatDecimal())	~41×
formatNumber	cached Intl formatter	new Intl.NumberFormat() per call	~40×
formatDecimal	cached Intl formatter	new Intl.NumberFormat() per call	~38×
roundToStep	no float noise	Math.round(v / step) * step (noisy)	0.5×

roundToStep is slower on purpose: it pays ~7 ns per call for exact results.