Website speed: how to pass the Core Web Vitals test without rebuilding everything

The cost of slowness

More than half of mobile visitors abandon a page that takes longer than 3 seconds to load. On a site with 3,000 monthly visits, that means hundreds of potential customers lost for nothing.

The three metrics that matter

• LCP — how long it takes for the main element to appear (usually the hero image). Target: under 2.5s.
• INP — how quickly the site responds to clicks. Target: under 200ms.
• CLS — how much the layout "jumps" upon loading. Target: under 0.1.

Optimisations in order of impact

1. Images

This accounts for 70% of the problem on Romanian websites.

• convert to WebP
• serve appropriate dimensions (not 3000px for a 400px card)
• `loading="lazy"` for everything below the first viewport
• set `width` and `height` to prevent layout shifts

2. Fonts

Limit yourself to two families and a maximum of 3-4 weights. Use `font-display: swap`.

3. Tracking scripts

Every added pixel costs. Keep only what you actually read in your reports.

4. Hosting

Cheap shared hosting alone can add 1-2 seconds. Check your server response time before optimising code.

5. Cache and CDN

Enable caching for static resources and deliver images via CDN.

How to check correctly

Test on real mobile data, not just in a desktop lab with fibre. Run the test three times and take the median.

What not to do

• Do not install five "optimisation" plugins in parallel; they will conflict with each other.
• Do not aggressively minify without testing forms afterwards.

Realistic outcome

On our projects, the order above usually halves the loading time within a few working days, without rewriting the website.