Loading speed

The time required for a web page to be fully displayed and interactive for the user, i.e. for all content (text, images, scripts, style sheets, etc.) to be available and usable. This is an essential factor in technical performance, but also a strategic lever for optimizing user experience and conversion rates.

🎯 Why it's crucial:

• A slow page generates frustration, increases the bounce rate, and can drastically reduce conversions, especially on mobile, where network constraints are greater.
• Google now considers speed as an SEO criterion, in particular through the Core Web Vitals.

📈 Impact on conversions :

• According to a Google x Deloitte study, 0.1 seconds of loading time can lead to a +8% to +10% increase in conversion rates.
  → Full study here (Think with Google).
• On mobile, a page that takes more than 3 seconds to load can see its probability of bounce increase by +32%, or even more to 5 seconds (+90%).

🛠️ Measuring tools :

• Google Lighthouse (and PageSpeed Insights),
• WebPageTest.org,
• Chrome DevTools ("Performance" tab),
• Core Web Vitals report via Search Console or GA4,
• Tools integrated with CDNs (Cloudflare, Fastly, Akamai...).

⚒️ Optimization levers :

• Image optimization (modern formats: WebP, compression, lazy loading),
• Minimization of CSS/JS files, removal of unnecessary code,
• Use of a CDN to bring content closer to users,
• Prioritization of on-screen content (Above the Fold),
• Reduce server calls (API, third-party scripts),
• Avoid slowdowns due to poorly loaded marketing tags or A/B testing tools.

🔍 In CRO:

Fast loading times:

• Reduce friction and make the user experience smoother,
• Improves A/B test performance (less flickering on client-side tests),
• Contributes to the site's perceived reliability and professionalism,
• Mechanically increases conversion, engagement and satisfaction rates.

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