The technical process of improving how quickly a website loads and responds for visitors — reducing page load times, improving Core Web Vitals scores and ensuring the site performs efficiently across all devices and connection speeds, directly benefiting both user experience and search engine rankings.
Google research shows that a one-second delay in mobile load time reduces conversions by up to 20%. Each additional second of load time increases bounce rate. Slow sites lose visitors before they see any content, with the commercial loss compounding with every visitor. Speed is a direct commercial variable, not just a technical concern.
Google’s three primary user experience metrics used as ranking signals: Largest Contentful Paint (LCP — how quickly the largest visible content element loads), Interaction to Next Paint (INP — how quickly the site responds to user input) and Cumulative Layout Shift (CLS — whether page elements shift unexpectedly as the page loads). Google uses these in its ranking algorithm.
Image optimisation (correct sizing, modern formats such as WebP, lazy loading), server-side caching (serving pre-rendered pages rather than generating on each request), a Content Delivery Network (CDN) for static assets, minification of CSS and JavaScript files, elimination of render-blocking scripts and upgrading to a high-performance hosting environment.
A technique that defers loading images and videos below the fold until the visitor scrolls near them, rather than loading all page assets simultaneously on initial load. Lazy loading reduces the initial page weight the browser must process before displaying the first screen of content, significantly improving LCP on image-heavy pages.
A Content Delivery Network is a globally distributed network of servers that stores cached copies of static assets (images, CSS, JavaScript) and delivers them from a server geographically close to each visitor. A visitor in Edinburgh receiving assets from a London server node loads them faster than from a server located in the US.
Google PageSpeed Insights (lab and field data, including Core Web Vitals), Google Search Console’s Core Web Vitals report (real-world field data from actual visitors), Lighthouse audits (detailed technical recommendations), GTmetrix (detailed waterfall analysis of asset loading) and Web Vitals Chrome extension for real-time monitoring during development.
Render-blocking occurs when scripts or stylesheets in the page head prevent the browser from displaying visible content until they have fully loaded. Fix by loading non-critical JavaScript with async or defer attributes, inlining critical CSS needed for above-the-fold content, and loading non-critical CSS after initial render.
WebP images are typically 25–34% smaller than equivalent JPEG or PNG files at comparable quality. AVIF achieves even smaller file sizes. Serving images in modern formats (with JPEG/PNG fallbacks for older browsers) reduces total page weight significantly, particularly on image-heavy product or portfolio pages.
Excessive or poorly coded WordPress plugins are a common performance drag — each active plugin adds database queries and PHP processing. Performance optimisation includes auditing all active plugins, removing unused ones, replacing resource-heavy plugins with more efficient alternatives and ensuring caching plugins are correctly configured to serve cached pages rather than dynamically rendered ones.
