Core Web Vitals: why load time decides your revenue
Every second of load time costs conversions. What LCP, INP and CLS actually measure, why Google cares — and how to concretely improve your scores.
Amazon famously calculated it years ago: 100 milliseconds of additional load time cost one percent of revenue. The same mechanics apply to your website, only more brutally — because unlike Amazon, you have no customer loyalty that forgives slow pages. Someone who clicks a Google result and stares at a white screen for three seconds is gone.
The three metrics Google measures
LCP (Largest Contentful Paint) measures when the main content becomes visible. Target: under 2.5 seconds. Most common killer: huge, unoptimized images.
INP (Interaction to Next Paint) measures how quickly the page reacts to clicks and input. Target: under 200 milliseconds. Most common killer: too much JavaScript — often from tracking scripts and page builders.
CLS (Cumulative Layout Shift) measures whether content jumps around while loading. Everyone knows it: you try to click and the button slips away. Target: under 0.1.
What actually helps — in this order
- Images in WebP or AVIF, correctly sized, with lazy loading. This alone solves half the problems on most websites.
- Radically reduce JavaScript. Every plugin, tracker and animation library has a price. Statically generated sites (like those built with Astro) structurally outperform WordPress with page builders here.
- Self-host your fonts and load them with
font-display: swap— no waiting for Google Fonts. - Caching and a CDN — included with good hosting.
Measure, don’t guess
Test your website with PageSpeed Insights — real field data, not just lab metrics. Scores below 90? That’s revenue lying on the street. We ship our projects with a Lighthouse score of 95+ — not out of vanity, but because those numbers feed directly into rankings and conversions.