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Web & MarketingApril 22, 20266 min de lecture

Website speed: the 5 optimizations that really make a difference

A slow site means lost customers and weaker rankings. These 5 concrete actions can cut your load time by 40 to 70% without rebuilding your site.

Key takeaways in 30 seconds

  • Images account for 60 to 80% of a page's weight — that is where the impact is biggest
  • A CDN can cut load time by 30 to 50% for visitors outside your region
  • Every third-party JavaScript (chat, analytics, pixel) adds 100 to 500 ms of load
  • Google Core Web Vitals have directly affected your search ranking since 2021

The direct link between speed and revenue

This is not just a technical matter. Website speed has a measurable impact on your conversions:

  • +1 second of load time = -7% conversions (Akamai)
  • 53% of mobile visitors leave if a page takes more than 3 seconds to load (Google)
  • Amazon estimated that every 100 ms of latency costs it 1% of revenue

And since 2021, Google factors Core Web Vitals (the real load speed users perceive) into its ranking criteria. A slow site is penalized twice: by the visitors who leave, and by Google ranking it lower.

Optimization 1 — Compress and convert your images

Images account for 60 to 80% of a web page's total weight on average. That is often where the gain is most spectacular.

Two concrete actions:

Convert to WebP: this modern format produces images of quality equivalent to JPEG/PNG at 25 to 35% less weight. Most modern CMSs handle it natively. For WordPress, plugins like Imagify or ShortPixel convert automatically.

Resize before uploading: uploading a 5000x4000px photo to display it at 800px wide loads 6 times more data than needed. Resize your images to their real display size before putting them online.

Target: no image above 200 KB on your site. Full-screen hero images can go up to 400 KB if it is a high-quality photo.

Optimization 2 — Lazy loading

Lazy loading means only loading images as they are about to enter the visitor's viewport — not all at once when the page loads.

In practice, a visitor landing on your homepage only needs the images visible without scrolling. Images further down the page can wait.

Setup is simple with the native HTML attribute: loading="lazy" on your tags. Modern frameworks like Next.js apply it automatically.

Typical gain: a 40 to 60% reduction in the initial weight the page loads.

Optimization 3 — Reduce third-party scripts

Every external script you add to your site — Google Analytics, Meta Pixel, Hotjar, Intercom, a chat widget, social share buttons — has a performance cost.

On average, a third-party script adds 100 to 500 ms of load time. If you have 6 or 7, you are already at 1 to 3 seconds of latency from those tools alone.

Concrete actions:

  • Audit your scripts: which do you actually use? Disable anything you do not need
  • Load them deferred with the defer or async attribute on