Core Web Vitals on WordPress: what actually moves the numbers
Caching plugins are the last 10%. Here is the 90% nobody wants to hear.
The uncomfortable truth about caching plugins
A caching plugin is the last ten percent of a performance project, not the first. If your theme loads six font weights, four sliders and a page builder that outputs nested divs forty levels deep, no plugin will save you. We have audited sites running three separate optimisation plugins that still failed LCP, because the underlying page weight was 6MB.
Start with what the page ships, not with how it is cached.
Largest Contentful Paint
On nearly every marketing site the LCP element is the hero image or headline. Serve the hero as a correctly sized AVIF or WebP, set explicit width and height, add fetchpriority="high", and never lazy-load it. Preload the single webfont used in the headline and self-host it — a Google Fonts request adds a whole extra connection before your text can paint.
If your hero is a video, show a poster frame first and load the video after the LCP has settled. Users cannot tell; Lighthouse can.
Cumulative Layout Shift
CLS is almost always uncommunicated size. Every image, embed, ad slot and iframe needs reserved dimensions. Cookie banners are the second offender — inject them as a fixed overlay, never as a block that pushes content down. Third is webfont swap: use font-display: swap with a metric-compatible fallback so the reflow is invisible.
Interaction to Next Paint
INP punishes heavy main-thread work. On WordPress that usually means the tag manager container, chat widgets and A/B testing scripts. Load them after user interaction or on idle, and question each one — most chat widgets cost 300KB of JavaScript to serve two enquiries a month.
A realistic order of work
Compress and correctly size images. Cut font weights to two. Defer third-party scripts. Reduce plugin count. Then add caching and a CDN. In that order it is usually a two-week job with durable results. Our WordPress versus headless piece covers when the platform itself is the constraint, and the technical SEO audit checklist shows where performance sits in a wider audit.
A 30-minute consultation and a written summary of what we would prioritise.
Keep reading
WordPress or headless? A decision framework for marketing sites
Editor experience, speed budgets and the real cost of each path.
The technical SEO audit checklist we actually hand to developers
Most audits are 90-page PDFs nobody reads. Here is the version we ship as tickets.
What a credible 90-day SEO plan looks like
Month one is not "rankings". Here is what should actually happen.