Core Web Vitals: why your site's speed drives sales
Google put a name on something your visitors have always felt: a sluggish site is irritating. Core Web Vitals are three measurements that score the real experience of a page. They are not about code, they are about patience. And online, patience is counted in seconds.
What LCP, INP and CLS measure, in plain terms
Three metrics, three simple questions from the visitor’s point of view.
LCP (Largest Contentful Paint) answers: “When does the page look ready?” It measures the time before the largest visible element appears, often an image or a heading. Target: under 2.5 seconds. Beyond that, the visitor feels they are waiting.
INP (Interaction to Next Paint) answers: “When I click, does it react?” It measures the delay between an action — a click, a tap — and the page’s visible response. Target: under 200 milliseconds. A site that reacts late feels broken.
CLS (Cumulative Layout Shift) answers: “Does the content move under my finger?” You go to tap a button, an image loads above it, everything shifts, and you tap the wrong thing. CLS measures those layout jumps. Target: a score under 0.1.
These three metrics come from real users, not a lab test. That is what makes them honest.
The real impact on conversion and ranking
Speed touches your business through two channels.
First, conversion. A visitor who waits gives up. It is mechanical: the longer the page stalls, the larger the share of people who leave before they even see your offer. On a site that generates sales or quote requests, every abandonment is one customer less.
Second, ranking. Google uses Core Web Vitals as one of its ranking signals. With equivalent content, a fast page moves ahead of a slow one. Speed does not replace good content, but it breaks the tie between two comparable pages.
The loop is virtuous: a fast site keeps more visitors, Google notices, ranks it higher, and sends you even more visitors.
The mobile and 4G context in the overseas territories
One nuance matters especially in the West Indies, in French Guiana and across the overseas territories: most visits happen on a phone, over mobile networks that do not always match mainland fiber.
A site tested “fast” on a wired desktop can fall apart on a mid-range smartphone over patchy 4G. Yet that is your customers’ real condition. A light site, loading little data and reacting quickly, stays usable where a heavy site becomes a waiting room.
Designing for mobile on an average network is not a constraint: it means aiming at the real majority of your local audience.
What we actually do to go fast
Speed is not magic, it is built by stacking good decisions:
- Compress and size images in a modern format, so they are neither blurry nor three times too heavy.
- Load the essentials first and defer the rest, so the page looks ready right away.
- Reserve space for elements before they load, to remove layout jumps.
- Limit third-party scripts, those trackers and widgets that often slow more than they add.
- Choose the right hosting and serve the site from a cache close to the visitor.
The takeaway: Core Web Vitals are not a Google whim, they are your visitors speaking. Measure your three scores with a free tool like PageSpeed Insights, on mobile, then fix the one in the red first. A point gained in speed is a point gained in revenue.