In 2024, Google published updated research showing that mobile sites loading in under 2.5 seconds had conversion rates 2x higher than sites loading in 4+ seconds. That gap has only widened. By 2026, user expectations have tightened further — partly because the fastest sites keep getting faster, and partly because AI-powered interfaces have trained people to expect near-instant responses.
“A one-second improvement in load time increases conversions by an average of 27%. For most SMEs, that translates to tens of thousands in recovered revenue.”
What the Data Shows
Across our client base, we measured the correlation between Core Web Vitals scores and lead generation. The pattern was consistent: businesses in the "good" range for all three metrics generated 3-4x more enquiries per thousand visitors than those in the "needs improvement" range. The relationship was not linear — it was exponential. Small improvements at the top end produced outsized returns.
The Three Metrics That Matter
- Largest Contentful Paint (LCP) — how quickly the main content appears. Target: under 2.5 seconds.
- Interaction to Next Paint (INP) — how responsive the page feels when you click. Target: under 200ms.
- Cumulative Layout Shift (CLS) — how much the page jumps around while loading. Target: under 0.1.
The good news: most performance problems are structural, not fundamental. Image optimisation, modern hosting, and removing unused JavaScript typically gets a site from "poor" to "good" in a single sprint. The investment pays for itself within weeks.
Written by Mihai Diaconita
Founder & CTO
Building conversion-focused websites since 2009. Passionate about data-driven design and helping businesses turn their websites into growth engines.
Stay sharp
Get conversion insights in your inbox
One email per month. Practical advice on conversion, performance, and building websites that actually generate revenue.
No spam. Unsubscribe anytime.