What are the three Core Web Vitals?
They are Google's three field-measured user-experience metrics. LCP (Largest Contentful Paint) measures loading — when the biggest element in the viewport renders; good is under 2.5s. INP (Interaction to Next Paint) measures responsiveness — how quickly the page reacts to input across the visit; good is under 200ms (it replaced FID in 2024). CLS (Cumulative Layout Shift) measures visual stability — how much the layout jumps; good is under 0.1.
All three are measured on real visitors, not just in a lab, which is why they reward decisions that help actual users rather than benchmark tricks.
Are they a ranking factor?
Yes, as part of page experience — but a tiebreaker, not a trump card. Genuinely helpful content with mediocre vitals still ranks; great vitals will not rescue a thin page. Treating Core Web Vitals as a ranking hack inverts the value.
The honest reason to fix them is the one that shows up in your own analytics: slow loads, laggy interactions, and jumping layouts cost attention, conversions, and trust. The ranking nudge is a bonus on top of a page people actually tolerate.
What actually moves them
Per metric: LCP improves with build-time or server rendering (see build-time rendering), right-sized images, fast hosting, and fonts that don't block the first paint. INP improves by shipping less JavaScript — smaller bundles, less main-thread work. CLS improves by reserving space: dimensioned images and media, no content injected above what's already rendered.
Notice the through-line — most fixes are about doing less on the client, not adding a plugin.
How do you measure them — field vs lab?
There are two kinds of measurement, and the difference is load-bearing. Field data (real users) comes from the Chrome User Experience Report, which feeds the Core Web Vitals report in Search Console — and field data is what Google actually uses for the ranking signal. Lab data (a synthetic test in a controlled environment) comes from Lighthouse and PageSpeed Insights and is for diagnosis.
Use them together: the field report tells you whether real users are having a bad time; the lab tools tell you why and let you test a fix before shipping. Chasing a green lab score while field data stays red is the common, avoidable trap.
Our approach: subtract weight
The site is built to ship as little as possible. Fonts are self-hosted rather than fetched from a third-party CDN, so there's no extra connection and round-trip before text renders. Content is delivered as finished HTML with little or no client JavaScript, so there's almost nothing for the main thread to do. Layout space is reserved so nothing jumps.
The principle generalizes past metrics: the fastest, most stable, most crawlable asset is the one you don't ship. That's the same subtraction discipline behind our platform work and behind generating only pages worth serving.