Page Speed
Page speed is how quickly a web page loads and becomes usable. It affects search rankings through Google’s page experience signals, but its biggest impact is on visitors: slow pages lose people before they read a word.
Why page speed matters
- User experience: visitors expect pages to load in a couple of seconds, especially on mobile.
- Conversions: faster pages generate more enquiries and sales. Every extra second of delay reduces conversion rates.
- Rankings: speed is measured through Core Web Vitals, a confirmed though modest ranking factor.
- Crawling: faster server responses let Google crawl more pages, which matters on larger sites (Crawl Budget).
- AI and other crawlers: slow or heavy pages may be fetched less completely by bots.
How to measure page speed
- PageSpeed Insights: shows real-user field data (if available) and a Lighthouse lab test with a performance score and suggestions.
- Core Web Vitals report in Google Search Console: shows which groups of pages pass on mobile and desktop.
- Chrome DevTools and Lighthouse: for detailed debugging.
- WebPageTest: for testing from different locations and connection speeds with waterfall charts.
Do not obsess over the Lighthouse score. It is a lab simulation. What counts for Google is field data from real users. PageSpeed Insights also includes accessibility, best practices and SEO audits; I wrote about these in PageSpeed Insights accessibility, best practices and SEO checks.
Key speed metrics
- Time to First Byte (TTFB): how fast the server responds.
- First Contentful Paint (FCP): when the first content appears.
- Largest Contentful Paint (LCP): when the main content appears.
- Interaction to Next Paint (INP): how quickly the page responds to input.
- Cumulative Layout Shift (CLS): how stable the layout is.
- Total Blocking Time (TBT): how long the main thread is blocked during load.
The most effective speed improvements
- Better hosting and caching: a fast server and full-page caching cut TTFB dramatically.
- A content delivery network (CDN): serves files from locations close to visitors.
- Image optimisation: compress images, use WebP or AVIF, size them correctly and lazy-load below-the-fold images (see Image SEO).
- Less JavaScript: remove unused scripts, defer the rest and limit third-party tags.
- Leaner CSS: remove unused styles and inline critical CSS.
- Efficient fonts: use fewer font files, subset them and preload key fonts.
- Fewer plugins: on WordPress, each plugin can add scripts and styles to every page.
- Modern protocols: HTTP/2 or HTTP/3 and compression such as Brotli.
Speed vs features
Every slider, chat widget, video background and tracking script has a cost. Before adding a feature, ask whether it earns its place. Often the fastest improvement is removing something nobody uses.
Mobile speed
Most searches happen on mobile, and Google uses Mobile-First Indexing, so test on a mid-range phone and a 4G connection, not just your office broadband. A page that feels instant on a desktop can be slow on a typical phone.
When to get help
If your Core Web Vitals still fail after the basics, the cause is often in the theme, page builder or hosting setup. My article on why Core Web Vitals fail despite a high PageSpeed score is a good next read.
Key Takeaways
- Page speed affects conversions most, and rankings through Core Web Vitals.
- Judge speed by real-user field data, not just the Lighthouse score.
- Hosting, caching, image optimisation and less JavaScript bring the biggest gains.
- Every widget and script has a performance cost.
- Test on a mid-range phone, not just a fast desktop.
Related Terms
Need a second opinion on your website? Ask for a free website SEO check, or keep learning in the SEO Encyclopedia.