What is page speed?
By Tom · Last reviewed · 6 minute read
Page speed is how quickly the content on your website loads and becomes usable, from the moment someone clicks a link to your site to when they can see and use the page. It matters for visitors, for enquiries and for search rankings, because Google treats page speed as a ranking factor.
On this page
Why page speed matters for your business
Every second counts. Slow websites cost you visitors, rankings and enquiries.
Visitors
People expect websites to load almost instantly. Google's own research has found that many mobile visitors give up on pages that take more than a few seconds to load. Every second of delay adds frustration and makes it more likely visitors will leave for a competitor. First impressions matter, and a slow website makes a business look less professional.
Search rankings
Google has used page speed as a ranking factor since 2010, and introduced Core Web Vitals as ranking signals in 2021. Slow websites can rank lower, so fewer people find your business. With mobile-first indexing, your mobile page speed is particularly important for SEO.
Enquiries and sales
Faster websites consistently turn more visitors into customers. Amazon reportedly found that every 100 milliseconds of delay cost it around 1% of sales. If your website brings in enquiries or sales, page speed directly affects your income.
Mobile performance
Most UK web traffic now comes from phones. Mobile connections are usually slower than broadband, and phones have less processing power. A site that loads quickly on a desktop can be painfully slow on a phone, and that's where most of your potential customers are.
How to measure your page speed
These free tools analyse your website's performance and show what needs fixing.
Google PageSpeed Insights
pagespeed.web.dev is Google's official tool. It analyses your page with both lab and real-world data, shows your Core Web Vitals scores and gives specific recommendations. Every website owner should know it.
- Pros: free, official Google data, practical recommendations, mobile and desktop testing
- Cons: can be overwhelming for beginners, and some recommendations need a developer
GTmetrix
GTmetrix gives a detailed performance analysis, with waterfall charts showing exactly what loads and when. It's great for finding specific bottlenecks.
- Pros: visual waterfall charts, history tracking, several test locations, video playback of the page loading
- Cons: the free version is limited to one location, and premium features cost money
WebPageTest
WebPageTest is an advanced testing tool used by professionals. You can test from real locations around the world, simulate different connection speeds and dig into the detail.
- Pros: real browser testing, global locations, connection throttling, filmstrip view
- Cons: the interface is less intuitive, and results can be technical
Google Search Console
Google Search Console is mainly an SEO tool, but it includes Core Web Vitals reports based on real visitor data from Chrome, showing performance issues across your whole site.
- Pros: real visitor data, a site-wide overview, free, points out problem pages
- Cons: you need to verify your site, data can be delayed, and it shows issues but not fixes
Core Web Vitals explained
Core Web Vitals are the three metrics Google uses to measure user experience. Meeting these targets helps your rankings.
| Metric | What it measures | Good | Needs work | Poor |
|---|---|---|---|---|
| LCP (Largest Contentful Paint) | How long the largest element (usually an image or block of text) takes to appear. This is what people perceive as the page loading. | Under 2.5 seconds | 2.5 to 4 seconds | Over 4 seconds |
| INP (Interaction to Next Paint) | How quickly the page responds when someone clicks, taps or types. A high INP makes a site feel sluggish. | Under 200ms | 200 to 500ms | Over 500ms |
| CLS (Cumulative Layout Shift) | How much the layout moves around as the page loads. A high CLS is frustrating when a button moves just as you try to tap it. | Under 0.1 | 0.1 to 0.25 | Over 0.25 |
INP replaced First Input Delay (FID) as a Core Web Vital in March 2024.
How to improve LCP
- Optimise and compress images
- Use modern image formats (WebP)
- Preload critical resources
- Upgrade to faster hosting
- Remove render-blocking resources
How to improve INP
- Reduce JavaScript execution time
- Break up long tasks
- Use a web worker for complex operations
- Minimise third-party scripts
- Defer non-critical JavaScript
How to improve CLS
- Always include width and height on images
- Reserve space for ads and embeds
- Avoid inserting content above existing content
- Use CSS aspect-ratio for media
- Load web fonts efficiently
What slows websites down
These are the most common issues I see when checking small business websites.
Unoptimised images (critical impact)
Problem: large, uncompressed images are the most common cause of slow websites. A single unoptimised hero image can add several megabytes to a page.
Solution: compress images, use modern formats like WebP and resize them to the size they're actually shown. Lazy load images further down the page.
Too many files to load (high impact)
Problem: every file (CSS, JavaScript, images, fonts) is a separate request to the server. Too many files slow loading down.
Solution: remove unnecessary plugins and scripts, and cut down the number of fonts and third-party tools you load.
Slow server response (high impact)
Problem: if your server takes too long to respond (a Time to First Byte over 600ms), everything else is delayed. Cheap shared hosting is often the cause.
Solution: upgrade to faster hosting, use server-side caching, optimise database queries and consider a CDN.
Render-blocking resources (high impact)
Problem: CSS and JavaScript files at the top of your page stop it from displaying until they've fully loaded.
Solution: inline critical CSS, defer non-critical JavaScript and load fonts asynchronously.
No browser caching (medium impact)
Problem: without caching, returning visitors must download every file again, which makes later page views unnecessarily slow.
Solution: set cache headers so browsers store static files, with long expiry times for files that rarely change.
Too many plugins (WordPress, medium impact)
Problem: each WordPress plugin adds code that has to load. Poorly written plugins can conflict with each other and slow your site.
Solution: remove plugins you don't use, choose lightweight alternatives and avoid plugins that load scripts on every page.
How to speed up your website
Practical improvements, with how hard they are and how much difference they make. Start with the easy, high-impact ones.
| Improvement | Difficulty | Impact | How |
|---|---|---|---|
| Optimise images | Easy | High | Compress images with tools like TinyPNG or ShortPixel, convert them to WebP and resize them to the size they're shown. |
| Enable caching | Easy | High | For WordPress, install a caching plugin like WP Rocket or LiteSpeed Cache. For other sites, set server cache headers. |
| Use a CDN | Medium | High | A content delivery network serves your files from servers close to your visitors. Cloudflare has a free tier. |
| Upgrade hosting | Medium | High | Move from basic shared hosting to a VPS or managed WordPress hosting. Choose UK servers for UK visitors. |
| Minify CSS and JavaScript | Easy | Medium | Remove unnecessary characters from code files. Most caching plugins do this. |
| Lazy load images | Easy | Medium | Only load images when they scroll into view. Modern browsers support this natively with loading="lazy". |
Tip: Not sure where your site stands? My free website audit checks your site's speed and gives you specific recommendations.
Questions people ask
What is page speed?
Page speed is how quickly the content on your website loads and becomes usable for visitors. It measures the time from when someone clicks a link or types your address to when they can see and interact with your page. It's usually measured in seconds and covers several metrics, including Time to First Byte (TTFB), First Contentful Paint (FCP) and Largest Contentful Paint (LCP). A fast page matters for both visitors and search rankings.
Why does page speed matter?
Page speed matters for three reasons. First, visitors: people expect websites to load within a few seconds, and many will give up on a slow mobile site. Second, SEO: Google uses page speed as a ranking factor, so slower sites can rank lower. Third, enquiries and sales: slower pages lose visitors before they get in touch or buy. For UK small businesses, a faster website means more people stay long enough to contact you.
How do I test my page speed?
The most popular free tool is Google PageSpeed Insights (pagespeed.web.dev), which tests mobile and desktop performance and gives specific recommendations. GTmetrix is another good option, with detailed waterfall charts showing what's slowing your site down. WebPageTest offers advanced testing from different locations and connection speeds. For ongoing monitoring, Google Search Console shows Core Web Vitals data for your whole site. Test on mobile as well as desktop, as mobile performance is often worse.
What is a good page speed?
Google considers a Largest Contentful Paint (LCP) within 2.5 seconds 'good', between 2.5 and 4 seconds 'needs improvement', and over 4 seconds 'poor'. For overall load time, aim for under 3 seconds on desktop and under 4 seconds on mobile. Your PageSpeed Insights score should ideally be 90 or above (green), though 50 to 89 (amber) is acceptable for most small business websites. The key is that people can use your site quickly.
Does page speed affect SEO?
Yes. Google confirmed in 2018 that page speed is a ranking factor for mobile searches, and in 2021 introduced Core Web Vitals as ranking signals. Slow websites can rank lower, get fewer visitors from search and see more people leave straight away. Because Google uses mobile-first indexing, your mobile page speed is particularly important. Improving page speed is one of the most useful technical SEO improvements you can make.
What are Core Web Vitals?
Core Web Vitals are three metrics Google uses to measure user experience. LCP (Largest Contentful Paint) measures loading: how quickly the main content appears. Good is under 2.5 seconds. INP (Interaction to Next Paint) measures responsiveness: how quickly the page responds when someone taps or clicks. Good is under 200 milliseconds. INP replaced the older First Input Delay (FID) metric in March 2024. CLS (Cumulative Layout Shift) measures visual stability: whether things jump around as the page loads. Good is under 0.1. Google considers these metrics when ranking your site.
How can I improve my page speed?
The most effective improvements are: optimise and compress images (often the biggest win), enable browser caching, minify CSS and JavaScript, use a content delivery network (CDN), choose fast web hosting, remove unnecessary plugins and scripts, lazy load images further down the page, and reduce server response time. For WordPress sites, a caching plugin and an image optimisation plugin can make a big difference with little effort.
Is mobile page speed different from desktop?
Yes, mobile and desktop speeds are measured separately and often differ a lot. Mobile connections are usually slower than broadband, phones have less processing power, and people on the move have patchy signal. Google uses mobile-first indexing, so your mobile page speed matters more for rankings. Always test and optimise for mobile first. Many sites score well on desktop but poorly on mobile, and that needs fixing.