Core Web Vitals Explained in simple terms. What they mean and why they matter.
What to keep your eye on, and how to improve them.
Updated 28 January 2026
Supposing you would like to improve your Core Web Vitals in the UK or internationally. Visit our homepage here to see proof first. It is updated daily, so you see the latest screenshots, not stale, lucky results. 👉Green Page Speed Tests.
They are the real-world tests that decide how fast and smooth your website feels to users.
They measure what happens on actual devices, not in a lab.
This guide will keep it easy to understand and explain what each vital means.
It will show how Green Page Speed keeps every score in the green.
We don’t rely on talk or theory. Our results are verified daily by Google PageSpeed Insights itself.
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A genuine endorsement of our performance work
You can read the official WPX appraisal below.
WPX APPRAISAL
One Job P/Day =FULL FOCUS
We only take on one website per day, because rushing speed work doesn’t cut it.
Your site gets our full focus, and every detail is tuned for performance.
This hands-on approach consistently changes your PSI scores to green. It boosts Google rankings.
You will attract more traffic, more visibility, and ultimately, more business.
However, the good news is that once you know how to use Google PageSpeed Insights properly,
You’ll uncover exactly what’s dragging your site down and how to fix it for good.
You pay upfront, and we do the work fast.
There are no hidden costs.
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Google’s own PageSpeed Insights site scores 94/93/100/92.
Our Green Page Speed site hits 100/100/100/100, almost daily – verified proof.
So, although we don’t promise scores like ours. (Although we aim to achieve them)
Green scores remain a strong possibility.
What Are Core Web Vitals
Core Web Vitals are three key performance metrics that affect how people experience your website.
They are LCP, CLS, and INP, and each one measures a different aspect of loading, stability, and interaction.
There’s also TTFB, which indirectly affects all of them.
A fast website is not just about speed tests. It is about real visitors enjoying a smooth experience.
Google tracks these signals to decide whether your site deserves to appear higher in search results.
A slow, unstable, or unresponsive site can cost you rankings, traffic, and sales.
TTFB – Time To First Byte
TTFB measures how long it takes for your browser to receive the first data from a web server.
It is like waiting for a waiter to acknowledge your order before the food even starts cooking.
A long wait means your server or hosting setup is slow to respond.
Common causes include poor hosting, missing caching layers, or the absence of a CDN.
At Green Page Speed, we reduce TTFB by improving server response.
Adding edge caching and optimising DNS and SSL handshakes.
We regularly bring TTFB down to under 100 milliseconds for our clients.
LCP – Largest Contentful Paint
LCP measures how quickly the main part of a page becomes visible.
This is usually the hero image or the largest text block above the fold.
If that image or headline takes four seconds to load, Google believes your site feels slow.
Even if the rest of the page appears later.
A poor LCP often comes from oversized hero images, render-blocking CSS, or slow hosting.
We address these issues by compressing images and lazy-loading assets below the fold.
It also covers serving files from lightning-fast servers.
Our daily proof screenshots will give you near-instant LCP results for both desktop and mobile.
CLS – Cumulative Layout Shift
CLS checks if anything on your page moves or shifts while it’s loading.
It is the score that punishes those annoying shifts when you go to click a button, and it suddenly moves.
High CLS happens when images or ads load without reserved space.
We prevent layout shifts by pre-defining image sizes.
Then, pre-load fonts and delay non-critical animations.
Our layout framework keeps every element firmly in place, ensuring CLS stays perfectly green on all pages.
TBT Total Blocking Time
TBT measures how long your page stays unresponsive while the browser is busy handling heavy scripts.
It is like trying to speak to someone who keeps pausing mid-sentence because they are overloaded with tasks.
A high TBT score indicates that the browser is blocked, and users may experience difficulties interacting with your page smoothly.
Common causes include large JavaScript bundles, unused scripts, slow third-party code, or too many tasks running on the main thread.
At Green Page Speed, we reduce TBT by removing unnecessary scripts and improving your code.
We will delay non-essential JavaScript, optimise critical tasks, and clean up render-blocking work.
We regularly bring TBT down to under 50 milliseconds for our clients.
INP – Interaction To Next Paint
INP is a newer metric that replaced FID.
It measures how fast your site reacts when a user interacts with it.
Such as clicking a button or typing in a form. A low INP means the site feels instant. A high INP makes it feel laggy or unresponsive.
We achieve low INP by deferring heavy JavaScript, removing bloated plugins, and limiting background tasks.
Every Green Page Speed site is built to react instantly. Visitors should never have to wait for their click to respond to the action…
Why Core Web Vitals Matter
Google uses Core Web Vitals as a ranking signal because they directly affect people.
Yes, how people experience your website.
A fast, stable, and responsive site improves engagement, increases trust, and reduces bounce rates.
At Green Page Speed, we focus on real improvements, not test manipulation.
Our clients see measurable ranking growth because Google recognises verified green results.
“We don’t just aim for green scores. We maintain them daily.”
28/01/26 / PageSpeed Insights mobile results show full green 100/100 scores How Core Web Vitals Work Together
All four metrics are connected.
When you lower TTFB, your LCP improves because the page starts rendering faster.
When you optimise images and stabilise layouts, CLS and INP improve naturally.
When scripts are deferred and caching is set correctly, everything feels instant.
We take a holistic approach that balances every factor.
That is why our sites stay green even after new updates or algorithm changes.
👉 Check out our PageSpeed Insights (2025) page for live examples and daily verified results.
Real-World Results (Proof Included)
Every improvement we describe here is proven every day.
Our screenshots show verified 100/100 results for Performance, Accessibility, Best Practices, and SEO.
Each result is timestamped and verified with Google’s own PageSpeed tool.
👉 Visit the Proof Wall to see more daily results.
How We Fix Core Web Vitals
We don’t install magic plugins or rely on shortcuts. Every site is tuned by hand.
Our process includes:
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Server optimisation: Faster DNS, reduced TTFB, and optimal caching layers.
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Image compression: Efficient WebP formats and responsive image delivery.
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Layout stabilisation: Defined dimensions for every visual element.
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Code refinement: Defer non-critical JS, clean CSS, and remove render-blocking files.
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Monitoring: We track ongoing PageSpeed Insights results for all clients.
This combination helps every site perform fast under real Google tests.
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FAQ – Core Web Vitals Explained
What are Core Web Vitals in simple terms?
They are Google’s way of measuring how fast and stable your website feels to users.
They focus on loading speed, visual stability, and interactivity.
How do Core Web Vitals affect SEO?
If your scores are poor, Google will view your site as slow or unresponsive, which can mean lower rankings.
Good scores help build trust and improve visibility.
What is a good score for LCP, CLS, and INP?
Google recommends LCP under 2.5 seconds, CLS below 0.1, and INP under 200 ms.
Our clients regularly meet or beat those thresholds.
How long does it take to fix Core Web Vitals?
Every site is different, but most clients see full green results within a few days after optimisation.
We then monitor monthly to maintain consistency.
See how different tools measure these metrics in our PageSpeed Insights comparison series.
Conclusion
At Green Page Speed, we live and breathe performance.
We explain it clearly, fix it properly, and prove it daily.
If you want real results backed by daily Google verification, let’s make your site green too.