Core Web Vitals is the set of metrics Google uses to measure the real experience of using a page — not a subjective "it feels fast", but concrete, measurable numbers. They have been one of the ranking signals for several years now, and at the same time one of the most neglected parts of SEO.
The three Core Web Vitals metrics
- LCP (Largest Contentful Paint) — how long it takes for the largest visible element on the page (a headline or hero image, for instance) to render fully. A good score: under 2.5 seconds.
- INP (Interaction to Next Paint) — how quickly the page responds to a user action such as a click or typing. A good score: under 200 milliseconds.
- CLS (Cumulative Layout Shift) — a measure of how much the layout jumps around while the page loads. A good score: under 0.1.
Why Google rewards this in rankings
Google has long stated that its goal is to show people pages that are not only relevant but also pleasant to use. A slow page whose layout jumps while you are reading is a worse experience — and Google has the data showing that people simply leave such pages. Core Web Vitals is an attempt to measure that with numbers rather than guesswork.
The most common mistakes that ruin the score
- Uncompressed, oversized images loaded at full resolution
- Unnecessary JavaScript libraries loaded on every page, even where they are not needed
- No lazy loading for content below the first screen
- Web fonts that block text rendering (missing `font-display: swap`)
- Adverts and third-party scripts (chat widgets, tracking pixels) loaded synchronously
- Elements with no reserved space (images, banners, buttons) that jump in once loaded
How to check your own score
The quickest way is Google's free PageSpeed Insights tool — you simply paste in the address. It is worth testing both the mobile and desktop versions, because the results can differ considerably. For comparison: the projects that leave our hands average 98/100 in Google PageSpeed — not because that is exceptional, but because performance is part of the process from the first line of code rather than a fix at the end.
What we do differently
- Next.js and a modern architecture instead of heavy template engines
- Image optimisation and compression on every launch
- The smallest possible number of JavaScript dependencies loaded at start
- Core Web Vitals testing as a standard stage before publication, not an option on request
If your current site scores poorly in PageSpeed, we can analyse it and point to specific fixes — sometimes that is a few hours of work rather than a rebuild from scratch. Write to us through the contact form.