Start With a Baseline
Before touching anything, run your site through Google PageSpeed Insights, WebPageTest and GTmetrix. Record every score and the specific opportunities flagged. The most common culprits on slow WordPress sites are unoptimised images, render-blocking scripts, poor hosting, and excessive plugin overhead. Address these in order of impact rather than randomly enabling optimisation plugins.
Hosting Is the Foundation
No optimisation compensates for poor hosting. If your Time to First Byte (TTFB) is above 400ms, the hosting conversation must happen first. Managed WordPress hosts like Kinsta, WP Engine or Cloudways include server-level caching, PHP 8.2+, and CDN integration that make a transformative difference. For most sites, switching hosts alone improves Lighthouse scores by 15–20 points.
Implement Multi-Layer Caching
Page caching serves pre-built HTML to anonymous users, eliminating PHP and database processing. Object caching with Redis stores query results in memory. Browser caching keeps static assets locally on return visits. Each layer targets a different bottleneck. WP Rocket handles all three cleanly with minimal configuration.
Image Optimisation in 2026
Every image should be served in WebP or AVIF format at the correct dimensions for each viewport. WordPress 6.x handles WebP conversion natively. Apply lazy loading to all images except the Largest Contentful Paint element — which should be preloaded with a link rel=preload tag to ensure it renders as fast as possible.
Reduce JavaScript & CSS
Many plugins load assets on every page even when only needed on one. WP Rocket's asset manager lets you restrict scripts to specific pages. Minify and defer remaining JS. Avoid page builders that generate excessive inline styles — a custom theme will always outperform a drag-and-drop equivalent on performance benchmarks.
Target Metrics
Aim for LCP under 2.5s, INP under 200ms, and CLS under 0.1 — Google's 'Good' thresholds. Re-measure after every significant change. Incremental measurement shows what's actually working and prevents wasted effort on changes that don't move the needle.