Page speed is several metrics, not one#
| Metric | Question it answers | Good |
|---|---|---|
| TTFB | How fast does the server respond? | ≤ 0.8 s |
| FCP | When does anything appear? | ≤ 1.8 s |
| LCP | When does the main content appear? | ≤ 2.5 s |
| INP | Does it respond quickly to taps? | ≤ 200 ms |
| CLS | Does the layout stay stable? | ≤ 0.1 |
LCP, INP and CLS are the Core Web Vitals used in Google’s page experience signals.
Biggest wins, in order#
- Hosting and caching — a fast server with full-page caching and a CDN.
- Images — correct sizes, WebP/AVIF, lazy-load below the fold, never the hero.
- JavaScript — remove unused plugins and scripts, defer the rest, delay third-party tags.
- CSS and fonts — fewer font files,
font-display: swap, remove unused CSS. - Theme — a lightweight theme instead of heavy page builders where possible.
Lab vs field data#
Lighthouse scores are simulations for debugging. Your real-world result is the field data in Search Console and the top of PageSpeed Insights, based on Chrome users over 28 days.
Guides: WordPress speed optimization, Core Web Vitals on WordPress.