The verdict in three sentences
In B2B, mobile speed has become a conversion and SEO factor in its own right: an LCP under 2.5 s and a mobile Lighthouse score above 90 change the game. A performance redesign in Amsterdam costs 6,000 to 16,000 EUR and rests on a strict performance budget (JS under 200 KB, AVIF images, SSR/edge). The return shows fast: +12 to 20% mobile conversion observed after optimization.
Cost per optimization
Not all optimizations carry the same effort or impact. Here are the most cost-effective items in a performance redesign.
| Optimization | Effort | Typical gain | Cost (EUR) |
|---|---|---|---|
| AVIF/WebP images + lazy loading | Medium | -30 to -50% weight | 800 - 2,000 |
| JavaScript (bundle) reduction | High | -0.5 to -1.5 s LCP | 1,500 - 4,000 |
| SSR / edge rendering | High | -200 to -400 ms TTFB | 2,000 - 5,000 |
| Preloading + optimized fonts | Low | -0.2 to -0.5 s | 400 - 1,200 |
| CDN + aggressive cache | Low | Stable TTFB under load | 500 - 1,500 |
| Audit + performance budget | Low | Durable framework | 800 - 2,300 |
Before/after mobile Lighthouse score
An average unoptimized B2B site often caps at 45-60 on mobile. Here is a realistic post-redesign trajectory.
| Metric | Before | After | 2026 target |
|---|---|---|---|
| Mobile Performance score | 48 | 92 | > 90 |
| LCP (Largest Contentful Paint) | 4.8 s | 2.1 s | < 2.5 s |
| TTFB (Time To First Byte) | 950 ms | 480 ms | < 600 ms |
| CLS (Cumulative Layout Shift) | 0.28 | 0.04 | < 0.1 |
| Transferred JS weight | 780 KB | 185 KB | < 200 KB |
Performance budget per resource
The performance budget sets caps per resource type. Exceeding it should become a blocker in code review.
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| Resource | Recommended cap | Main lever |
|---|---|---|
| JavaScript (total) | < 200 KB | Code splitting, tree shaking |
| Images (per page) | < 500 KB | AVIF, responsive sizing |
| Web fonts | < 100 KB | Subsetting, preload |
| Critical CSS | < 50 KB | Inline critical, purge |
| Total requests | < 50 | Bundling, cache |
Mini case study
Mark, marketing director of a B2B industrial SME in Amsterdam, rebuilds his catalog site. He invests 11,000 EUR in a performance redesign. Before, mobile LCP was 4.8 s and the quote-request conversion rate was 1.8%. After optimization (AVIF images, JS bundle down to 185 KB, edge rendering), LCP falls to 2.1 s and mobile conversion climbs to 2.2%, i.e. +22%. Across 14,000 mobile visits/month, that means 56 extra quote requests per year. At a 20% close rate and an 8,000 EUR average deal, the estimated annual impact exceeds 89,000 EUR in additional pipeline.
FAQ
Does speed really affect SEO? Yes. Core Web Vitals (LCP, CLS, INP) are Google ranking signals, and a fast page is crawled and converts better. It is a double traffic-and-conversion benefit.
Do I have to go SSR/edge? Not always, but for a dynamic B2B site, server or edge rendering clearly cuts TTFB. A static (SSG) site is even faster when the content allows it.
Which item pays off most? Often JavaScript reduction and image optimization: they are the two biggest contributors to mobile LCP, for controlled effort.
How long does a performance redesign take? Budget 3 to 8 weeks depending on site size and existing technical debt. A preliminary audit defines the exact scope.
How do you keep performance over time? By enforcing a performance budget in continuous integration: any cap breach (JS, images) blocks the production deploy.
Let's scope your project. Send us your URL and current Lighthouse scores: we audit and quote the performance redesign with guaranteed LCP/TTFB targets. 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.
