If you have ever run your website through a speed test and been handed a page of acronyms, you are not alone. Core Web Vitals are Google’s way of measuring how a page feels to a real visitor: how quickly the main content appears, how fast the page responds when you tap, and whether things jump around while loading. They are worth understanding because they affect both your customers’ experience and, to a degree, how your site performs in search.
The three Core Web Vitals in plain English
Largest Contentful Paint (LCP): how fast does the main content appear?
LCP measures how long it takes for the biggest visible element, usually a hero image, headline or large block of text, to load. Google considers 2.5 seconds or less to be good. A slow LCP feels like staring at a blank or half-built page, and visitors often leave before it finishes.
Interaction to Next Paint (INP): how quickly does the page respond?
INP measures how quickly a page reacts when someone taps a button, opens a menu or types in a field. Google considers 200 milliseconds or less to be good. A poor INP feels like a page that has frozen or is ignoring you. INP replaced an older measure called First Input Delay in 2024.
Cumulative Layout Shift (CLS): does the page jump around?
CLS measures unexpected movement while the page loads, such as text shifting down because an image or advert appeared late. Google considers a score of 0.1 or less to be good. A bad CLS is the reason you tap one button and hit another by mistake.
Why they matter to a business
- Customer experience. Fast, stable pages make it easier to read, book and buy. Slow, jumpy pages cost enquiries.
- Search visibility. Page experience is one of many signals Google uses. It will not rescue weak content, but a very poor experience can hold a good page back.
- Mobile users. Most local visitors are on phones, often on slower connections, where problems are amplified.
Treat these measures as a way to find real problems, not a score to chase for its own sake.
How to check your own site
- Google Search Console has a Core Web Vitals report based on real visitor data, grouped by page type.
- PageSpeed Insights tests a single page and shows both lab results and real-world data when enough visitors exist.
- Your own phone. Open your site on mobile data and use it as a customer would. If it feels slow to you, it feels slow to them.
The usual causes of poor scores, and what fixes them
Oversized images
The single most common cause of slow pages. Photos straight from a camera can be many times larger than needed. Resize them to the size they are displayed, use modern formats and load images below the fold only when needed.
Too many plugins and heavy page builders
Every plugin and effect adds code the browser must process. Remove what you do not use and choose lean tools. Our post on why a faster website is usually a simpler website expands on this.
Slow hosting
If the server is slow to respond, nothing else can make up for it. Quality website hosting with caching and modern server software is a foundation for good scores.
Third-party scripts
Chat widgets, tracking tags, review feeds and advert code can slow a site and cause layout jumps. Keep the ones that earn their place and load the rest sensibly.
Fonts and layout
Custom fonts that load late can shift text. Reserve space for images, embeds and banners so the layout does not move when they arrive.
Speed is not a one-off project
Sites slow down over time as content, plugins and tracking tools accumulate. Regular checks and clean-ups keep performance healthy, which is part of what our website maintenance covers. If a site has become slow and hard to work with, you may be dealing with the symptoms described in our post on signs your website has become a bottleneck.
Frequently asked questions
Do Core Web Vitals directly affect my Google ranking?
They are one of many signals, and relevance and content quality matter more. But a consistently poor experience can hurt, and good speed helps conversions regardless of rankings.
What is a good PageSpeed score?
Scores are a guide, not the goal. Focus on whether real users have a good experience, and use the report to find specific fixes.
Can I fix this myself?
Some fixes, like compressing images and removing unused plugins, are straightforward. Others, such as code, hosting and caching changes, usually need a developer.
Web Paste builds fast websites for Waikato and New Zealand businesses and can review your current site’s performance. See our website design and development work or get in touch for a speed review.
