The verdict in three sentences
For a corporate B2B site already in production, a one-off performance project (audit + optimizations) costs between GBP 5,000 and 12,000 and ships in 3 to 6 weeks, versus a full technical rebuild at GBP 30,000 and up. The targets are LCP < 2.5s, INP < 200ms, CLS < 0.1 on mobile 4G. The return shows fast: +8 to +20% conversion on quote-request forms plus better Google rankings.
What a Core Web Vitals project covers
A performance project is not a rebuild: you keep the site and fix the bottlenecks. The audit flags uncompressed images, missing lazy loading, render-blocking third-party scripts, and the absence of cache and CDN. Remediation tackles these by impact on LCP and INP.
| Item | Scope | 2026 range (EUR HT) | Timeline |
|---|---|---|---|
| Perf audit + prioritized plan | Lighthouse, WebPageTest, backlog | 1,500 - 3,500 | 3-5 d |
| Image optimization (WebP/AVIF, srcset) | Compression, sizing, lazy load | 1,200 - 2,800 | 1 wk |
| Cache + CDN | Edge cache, headers, purge | 800 - 2,000 | 3-5 d |
| Third-party & JS | Defer, code-splitting, removal | 1,500 - 3,500 | 1-2 wk |
| Monitoring + re-test | 30-day monitoring, report | 500 - 1,200 | ongoing |
One-off project or technical rebuild?
The choice depends on technical debt. A recent, misconfigured site is cheap to fix; an aging CMS sometimes justifies a rebuild.
| Criterion | One-off perf project | Technical rebuild |
|---|---|---|
| 2026 budget (EUR HT) | 4,000 - 10,000 | 25,000 - 60,000 |
| Timeline | 3 - 6 weeks | 3 - 5 months |
| SEO risk | Low (URLs kept) | To manage (redirects) |
| Expected perf gain | +30 to +60 Lighthouse pts | Start from scratch |
| When to pick it | Low/medium debt | Obsolete CMS, blocking stack |
| London benchmark | 5,000 - 12,000 GBP | 30,000 - 70,000 GBP |
Mini case study
Thomas, IT director of an industrial equipment maker in London (180 staff), runs a B2B site generating 60 quote requests a month. Mobile LCP sits at 4.8s and Google has downgraded his ranking. He commissions a performance project at GBP 7,200. After 4 weeks LCP drops to 2.1s and INP to 150ms. Visitor-to-request conversion rises 12%, i.e. 7 extra requests per month. At a 20% close rate and an average deal of GBP 18,000, that is roughly GBP 25,000 in additional monthly revenue: the project pays for itself in days.
FAQ
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How much is a standalone Core Web Vitals audit?
Between GBP 1,500 and 3,500 in 2026 depending on depth. It delivers Lighthouse scores, a WebPageTest report and a backlog prioritized by impact. It is the required step before any remediation quote.
How long until SEO results appear?
Core Web Vitals are recomputed by Google from field data (CrUX) over a rolling 28 days. Allow 4 to 8 weeks after go-live to see the full ranking effect.
Is the +8 to +20% conversion gain guaranteed?
It is a 2026 order of magnitude from our projects and sector studies. The real effect depends on your starting point: a very slow site gains more than an already-decent one.
Do I need to change hosting?
Not always. A well-configured edge CDN and cache often suffice. Changing host is only advised if server response time (TTFB) stays high after optimization.
How do you keep performance from degrading?
We add a performance budget in the CI pipeline and 30-day monitoring. Every new release is automatically tested against the LCP/INP/CLS thresholds.
Let's scope your project. Share the URL, your stack and current Lighthouse scores: we will scope the work and an indicative budget (EUR 4,000-10,000 / GBP 5,000-12,000). 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.
