content-visibility Measured: One CSS Line, 15x Less Layout
Same HTML, same bytes, one CSS line, and forced layout dropped from 27.3ms to 1.8ms. I traced content-visibility: auto in Chrome and mapped its a11y traps.
Tags
Core Web Vitals
4 posts
Measuring INP: one click cost 264ms, chunking it got 56ms
INP replaced FID in Core Web Vitals in 2024. I ran 220ms of work as one blocking task versus sliced with scheduler.yield: 264ms fell to 56ms, in code and logs.
Cutting CLS from 0.559 to 0.014, measured
I built the same page two ways and measured both. Reserved image boxes and pre-placed slots dropped Cumulative Layout Shift from 0.559 (POOR) to 0.014 (GOOD).
A 117KB hero with a 1.2s LCP: the browser found it too late
Slow LCP is rarely about image weight — it is about when the browser finds it. I traced a CSS hero invisible to the preload scanner and cut LCP 1247ms to 109ms.