What Are Core Web Vitals and Why They Matter (Made Simple)

You may have seen it in a report from Google or from a marketer: "improve your Core Web Vitals." It sounds technical, but it is actually a simple thing - how fast and pleasant your website is to use. And that affects both your rankings in Google and whether a visitor buys from you or leaves.

The three numbers that matter

Core Web Vitals are three measurable indicators of the website usage experience that Google takes into account in its SEO evaluation:

LCP (Largest Contentful Paint) - how fast the main content appears. How many seconds it takes before a visitor sees the essentials (for example a large image or a heading). Target: under 2.5 seconds.

INP (Interaction to Next Paint) - how fast the website responds to a click. When a user clicks or types, how quickly something happens. It replaced the older FID metric. Target: under 200 ms.

CLS (Cumulative Layout Shift) - how much the content "jumps around." You know the feeling: you want to click a button and at the last moment the page shifts because an ad finished loading. Target: below 0.1.

Why it matters

1. Google takes it into account. Core Web Vitals are part of the page quality assessment. With otherwise equal content, a faster website has an advantage.

2. A slow website loses customers. Every extra second of loading reduces the chance that a visitor stays. For an e-shop this translates directly into revenue.

3. Credibility. A fast, smooth website looks professional. A slow and jumpy one looks cheap - no matter how much it cost.

Why websites tend to be slow

The most common causes we see in practice:

• Page builders (Elementor, WPBakery) - convenient, but they generate a lot of unnecessary code.
• Unoptimized images - a photo from a camera can be 5 MB; on the web a fraction of that is enough.
• Too many plugins that load on every page.
• Slow or cheap hosting.
• No caching and no modern image formats (WebP/AVIF).

How to measure Core Web Vitals

You have several options for finding out how your website is doing:

PageSpeed Insights - the fastest way. You enter the website address and immediately see the Core Web Vitals score. Green = fine, orange/red = room for improvement. Run the test for mobile too - the result is usually worse there. PageSpeed also suggests specific optimizations.

Search Console (Google Search Console) - if your site is indexed, it offers a "Core Web Vitals" report with real data from actual users. This is field data, not lab testing - it reflects reality better. Look at the 28-day average.

Chrome User Experience Report (CrUX) - anonymized data from millions of real visitors. Broken down by region, device type and connection type. If you want to know how your website appears to real people in Europe, CrUX is the source.

The difference between lab and field data: A PageSpeed test runs your website in a standard environment (laptop performance, 4G network). Real users have various devices and internet speeds. That is why field data (Search Console, CrUX) is more important - you see how it looks in practice.

How to improve Core Web Vitals

If PageSpeed Insights or Search Console shows orange or red, here are concrete steps to improve.

How to improve LCP (content loading speed)

1. Optimize images. A large image on the home page is the most common cause of slow LCP. Reduce the file size (compress JPG/PNG) or use a modern format (WebP/AVIF). Web images do not need to be as high resolution as print - 1920x1080 px is usually enough.

2. Reduce the time to first byte (TTFB). If the server takes a long time to process a request, even fast content arrives late. Check that you have quality hosting (not a cheap shared one). A CDN (Content Delivery Network, for example QUIC.cloud) speeds up content delivery because it caches it close to the user.

3. Defer non-essential JavaScript. Heavy scripts that load right at the start block content. If you do not need a given script during rendering, defer it using the defer or async attribute.

4. Avoid loading="lazy" on the LCP image. The LCP image needs to load fast. If you have marked it as lazy, it will only slow down.

How to improve INP (response to a click)

1. Reduce the amount of JavaScript. A lot of JavaScript means longer parsing and compilation time. The browser has to read and compile all the JS before it can safely run your code. If you have many plugins, check whether you really need all of them.

2. Break long tasks into smaller ones. If a script does a lot of work at once, the entire JavaScript thread gets blocked and the page does not respond to clicks. Use setTimeout or requestAnimationFrame to split the work into smaller pieces.

3. Optimize event handlers. If something happens on a click (for example a calculation or a DOM change), make it as fast as possible. Avoid unnecessary DOM recalculations right after a CSS change.

4. Check how many plugins you run. Plugins are useful, but each plugin = more JavaScript. You have a plugin for analytics, for popups, for reviews... each of them runs in the background and does work. If you have 15+ plugins, that is a problem.

How to improve CLS (content stability)

1. Add dimensions to images. Assign the width and height attributes or CSS aspect-ratio to every image. The browser then knows in advance how much space the image takes up and this does not create content shifts.

2. Reserve space for dynamic content. If content is inserted into the page only during loading (ads, videos, widgets), set a minimum height (min-height) or aspect-ratio on the container. The content then loads without shifting everything else.

3. Avoid animations that shift content. Animating properties such as top, left or box-shadow causes repaints and shifts. Instead, use transform, which changes position without affecting the rest of the content.

4. Watch out for fonts. If a web font loads slowly, the browser first displays a fallback font (System Font), and when the web font loads, all the text gets larger or smaller. Configure font-display: optional or font-display: swap as appropriate.

Core Web Vitals and WordPress

Many WordPress websites are built with page builders (Elementor, WPBakery, Divi). These tools are convenient - everything is clicked together in a GUI - but at the cost of quality: they generate a lot of unnecessary JavaScript and CSS, which worsens Core Web Vitals. If you have a website built in Elementor and you see a red score, it is often tied to the page builder, not to your content.

The fastest WordPress websites (the ones that reach Green in PageSpeed) are built without a page builder - with clean code and a custom theme. That is also why many old websites migrate from Elementor to clean WordPress - the performance comes back even without further optimizations.

If we build your website from the ground up, we factor in Core Web Vitals from the start. If you have an existing website with poorer results, SEO optimization includes analyzing and fixing Core Web Vitals problems.

What to do about it

Some of it can be solved quickly (image optimization, caching), some requires changing how the website is built. We build websites with a focus on performance from the ground up - without the unnecessary ballast of page builders. And when you have an existing slow website, as part of SEO we can find what is slowing it down and fix it.

Want to know what is slowing your website down? Write to us - we will take a look and tell you specifically what to improve.