The verdict in three sentences
Core Web Vitals are no longer a technical detail: they affect both SEO and conversion directly. In 2026 a B2B site should target LCP < 2.5s, INP < 200ms, CLS < 0.1. Investing EUR 2,000-6,000 in performance during a redesign pays back through +8-15 % conversion per second saved and -20 % bounce rate.
The three metrics to steer
Since INP replaced FID, interaction responsiveness is central. Here are the 2026 thresholds and levers.
| Metric | "Good" threshold | Main lever | Indicative cost |
|---|---|---|---|
| LCP (loading) | < 2.5s | WebP/AVIF images, CDN, lazy load | EUR 600-1,800 |
| INP (responsiveness) | < 200ms | Lean JS, code splitting | EUR 700-2,200 |
| CLS (stability) | < 0.1 | Media dimensions, fonts | EUR 300-900 |
| TTFB (server) | < 600ms | Hosting, edge cache | EUR 400-1,100 |
| Total budget | EUR 2,000-6,000 |
The business impact of speed
Performance is not cosmetic: it moves the conversion funnel numbers.
| Metric | Slow site (LCP 4.5s) | Optimised site (LCP 2.2s) |
|---|---|---|
| Bounce rate | 55 % | 44 % (-20 %) |
| Conversion rate | 1.8 % | 2.3 % (+28 %) |
| Pages/session | 2.1 | 3.0 |
| CDN hosting cost | EUR 15-30/mo | EUR 40-90/mo |
| Mobile PageSpeed score | 48/100 | 92/100 |
Mini case study
Need a professional website?
Kolonell builds websites that attract clients, optimized for the Sénégalese market. Free quote in 2 minutes.
Sophie, digital lead at an industrial SME in Nantes, gets 6,000 visitors/month at 1.8 % conversion, i.e. 108 leads. After optimisation (LCP from 4.4s to 2.1s), conversion rises to 2.3 %, i.e. 138 leads, +30 leads/month. At an average B2B deal of EUR 4,200 and 15 % closing, that's 4.5 extra sales/month, ~EUR 19,000 in revenue. The performance work cost EUR 4,500: paid back in under a month.
FAQ
What budget to optimise the Core Web Vitals of a B2B site? Expect EUR 2,000-6,000 depending on site state and CMS. A full redesign builds in performance from the start, reducing the extra cost.
What is INP and why does it replace FID? INP (Interaction to Next Paint) measures real responsiveness across the whole session, not just the first interaction. Target: < 200ms. It penalises JavaScript-heavy sites.
Does a good PageSpeed score guarantee better rankings? It helps but isn't enough: content, backlinks and relevance remain decisive. Performance is a baseline factor and a conversion multiplier.
How much does suitable CDN hosting cost? In 2026, expect EUR 40-90/month for a solid CDN and edge cache, versus EUR 15-30 for classic shared hosting.
How much conversion do you gain per second of load time saved? The observed order of magnitude is +8-15 % conversion per second saved, with a stronger effect on mobile.
Let's scope your project. Send us the URL to audit and your targets (LCP, conversion) and we'll quote the performance package within your redesign. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.
Mohamed Bah
Fondateur, Kolonell
Passionate about digital and entrepreneurship in Africa, Mohamed has been helping Sénégalese businesses with their digital transformation since 2020. Founder of Kolonell, he believes every SME deserves a professional and accessible online présence.
