The verdict in three sentences
Core Web Vitals are not a developer's whim: they are three metrics Google uses to rank your site and that your prospects feel on every click. Taking a B2B website from red to green on mobile improves both ranking and conversion, with a measured B2B gain of 15 to 25 %. In Berlin, where a large share of traffic arrives on variable mobile networks, this effort has a direct ROI and a controlled budget of EUR 1,500 to 3,000.
The 2026 targets to hit on mobile
Google has fixed three indicators. In 2026, the "Good" threshold must be met on mobile, not just desktop, because the index is mobile-first.
| Metric | 2026 "Good" threshold | What it measures | Main lever |
|---|---|---|---|
| LCP (Largest Contentful Paint) | < 2.5 s | Render of the largest element | WebP/AVIF images, CDN |
| INP (Interaction to Next Paint) | < 200 ms | Responsiveness to clicks | Reduce blocking JS |
| CLS (Cumulative Layout Shift) | < 0.1 | Visual stability | Fixed image/ad dimensions |
| Page weight | < 1.5 MB | Total downloaded volume | Compression, lazy loading |
| TTFB (server) | < 600 ms | Server response time | Cache, fast hosting |
INP replaced FID in 2024 and remains the hardest to hold on script-heavy sites (chat, tracking, ads).
Optimization levers and their impact
Each lever has a different cost and gain. We prioritise those that unblock mobile LCP, often weak point number one.
| Lever | Effort | Typical gain | Indicative cost (EUR) |
|---|---|---|---|
| AVIF images + lazy loading | Medium | -40 to -60 % weight | 400-800 |
| Edge CDN (caching) | Low | -30 to -50 % TTFB | 300-600 + sub |
| Defer/reduce third-party JS | High | INP halved | 600-1,200 |
| System fonts (no web font) | Low | -200 to -400 ms LCP | 100-200 |
| Space reservation (CLS) | Medium | CLS < 0.1 | 300-600 |
A full project combining these levers costs EUR 1,500 to 3,000 for a B2B brochure or catalogue site, paying back within a few months through conversion.
Mini case study
Lena, e-marketing lead at a Berlin B2B services SME, has a site loading in 4.1 s on mobile with LCP at 3.8 s. The site gets 12,000 visits/month and converts at 1.8 %, i.e. 216 leads. We bring the load down to 2.0 s. Applying a cautious 18 % conversion lift, the rate reaches 2.12 %, i.e. 254 leads, +38 leads/month. At an average margin of EUR 35 per lead, that is EUR 1,330/month gained. The EUR 2,200 project pays back in under two months.
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FAQ
Why optimise mobile first?
Because Google has indexed mobile-first since 2019 and most B2B traffic in Berlin arrives on smartphones. A good desktop score never offsets a poor mobile one.
How long to reach green?
A standard project takes 2 to 4 weeks of development, plus 28 days for field data (CrUX) to update in Search Console.
AVIF or WebP in 2026?
AVIF offers 20 to 30 % less weight than WebP at equal quality and is now supported by all modern browsers. We serve AVIF with a WebP fallback.
Does a good score guarantee better ranking?
Core Web Vitals are one ranking factor among others, but above all a conversion factor: the 15 to 25 % business gain is often more profitable than the SEO gain alone.
What minimum budget should I plan?
A worthwhile project starts at EUR 1,500; a heavy site with many third-party scripts can reach EUR 3,000. Below that, you only treat symptoms.
Let's scope your project. Core Web Vitals optimization of a B2B site, indicative budget EUR 1,500-3,000, target LCP <2.5 s on mobile in 3-4 weeks. 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.
