How to actually improve your GTmetrix score.

GTmetrix is the speed test most UK agencies and clients still default to, and for good reason: it bundles Google's Lighthouse data with its own Structure audit, gives you a waterfall view, and lets you test from different locations on different connection profiles. But the report can be intimidating. There are dozens of audits, three different scores, four headline metrics, and twenty recommendations. Where do you actually start?

This page walks through every meaningful GTmetrix audit in order of impact: the cache policy headers, render-blocking resources, image format and sizing, layout shift, TLS and HTTP version, and the dreaded "Reduce JavaScript execution time" warning that haunts every WordPress site running 25 plugins. We explain what each one means, why it matters, and exactly how we fix it.

The short version: there are about six things that make WordPress sites slow, and GTmetrix's audits are essentially a checklist for fixing them. Get caching headers right, serve images in WebP or AVIF at the correct dimensions, defer or eliminate render-blocking JS, lock down CLS by reserving space for media and ads, move to TLS 1.3 + HTTP/3, and audit your third-party scripts brutally. Do those six things and your A grades will follow.

If you'd rather not spend a weekend reading Lighthouse documentation, we do this for a living — typically taking a 40 Performance score to 95+ in under a week, with a written report of every change made.