A slow page kills conversions. One extra second of load time means a 7 % drop in conversion. Technical page optimisation is not an IT department project — it is a marketing priority.
In brief
- LCP under 2.5 seconds is the target.
- Images: WebP format plus lazy loading.
- JavaScript: minify and defer.
- Test with PageSpeed Insights and Google Search Console.
The Core Web Vitals metrics
- LCP (Largest Contentful Paint) — the load of the main image or text. Under 2.5 s is good.
- INP (Interaction to Next Paint): how quickly the page responds to a click. Under 200 ms.
- CLS (Cumulative Layout Shift): how much the page jumps while loading. Under 0.1.

Optimising images
- Use the WebP format (30–70 % smaller than JPG)
- Upload images at the right size (do not load a 4,000 px image to show it at 400 px)
- Use lazy loading for images below the fold
- Preload the hero image (rel=”preload”)
JavaScript and CSS
- Remove unused plugins
- Minify JS and CSS
- Defer non-critical JS (async, defer)
- Use the critical CSS technique
Other important things
- Quality hosting (Kinsta, WP Engine for WordPress)
- A CDN in use (Cloudflare, BunnyCDN)
- A caching plan (WP Rocket, W3 Total Cache)
- Fast DNS (Cloudflare DNS)
- Font optimisation (font-display: swap)

Frequently asked questions
Which tool should I test with?
PageSpeed Insights (pagespeed.web.dev) is free and reliable.
WordPress is slow — what helps most?
WP Rocket plus Cloudflare plus WebP images lifts most sites to a mobile score of 90+.
Is speed an SEO factor?
It is. Core Web Vitals is an official Google ranking factor.
Related reading
Read these related articles and service pages too:
External sources:
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