A slow website frustrates visitors, lowers conversions and can hold back your search rankings. Google measures real-world user experience through a set of metrics called Core Web Vitals. Here’s what they mean and how to improve them.
The three Core Web Vitals
Largest Contentful Paint (LCP): loading
How long it takes for the main content (usually the hero image or headline) to appear. Good: 2.5 seconds or less.
Interaction to Next Paint (INP): responsiveness
How quickly the page responds when someone taps, clicks or types. INP replaced First Input Delay (FID) as a Core Web Vital in March 2024. Good: 200 milliseconds or less.
Cumulative Layout Shift (CLS): visual stability
How much the page layout unexpectedly jumps around while loading. Good: 0.1 or less.
How to check your site
- PageSpeed Insights shows both lab data and real-user data for your pages.
- Google Search Console has a Core Web Vitals report for your whole site.
- Lighthouse, built into Chrome DevTools, helps diagnose specific issues.
Practical ways to speed up your website
Optimise images
Images are often the biggest files on a page. Use modern formats like WebP or AVIF, serve appropriately sized images for each screen and lazy-load images below the fold.
Ship less JavaScript
Heavy scripts slow both loading and interactivity. Remove unused plugins and third-party widgets, and load non-essential scripts later. Frameworks like Astro ship zero JavaScript by default for content pages.
Use a CDN and caching
A content delivery network serves your site from locations close to your visitors. Proper caching means returning visitors load pages almost instantly.
Reserve space for images and ads
Always set width and height on images, embeds and ad slots so the layout doesn’t jump when they load. This directly improves CLS.
Choose good hosting
Cheap, overloaded shared hosting can undo every other optimisation. Fast server response times are the foundation.
Be careful with fonts
Limit the number of font families and weights, self-host fonts where possible and use font-display: swap so text appears immediately.
Does speed really affect SEO?
Page experience is one of many signals Google uses. Great content still matters most, but when competing pages are similarly relevant, a faster and more stable experience helps. More importantly, faster sites convert better, so the effort pays off either way.
Want a faster website? Our website development service builds performance in from day one, and our maintenance plans keep it fast.
- seo
- performance
- core web vitals
Written by
Wiesella Team
Digital Solutions Team at Wiesella, sharing practical advice on software, websites and digital marketing for growing businesses.