The verdict in three sentences
A Miami business site with a 4.2 s LCP loses customers before it even loads: +1 second of load time = -7 % conversion. A Core Web Vitals audit costs 900 to 2,500 EUR in 2026, and the optimizations (WebP/AVIF images, lazy-load, CDN, cache) 1,500 to 4,000 EUR, delivered in 2 to 4 weeks. The targets are clear: LCP < 2.5 s, INP < 200 ms, CLS < 0.1.
What the audit covers and what it costs
A serious performance audit goes beyond a raw PageSpeed score. Here is the 2026 breakdown for a 10-to-30-page business site.
| Item | 2026 Price (EUR) | Timeline |
|---|---|---|
| Full Core Web Vitals audit | 900 - 2,500 | 3 - 5 days |
| Image optimization (WebP/AVIF) | 400 - 1,000 | 3 - 6 days |
| Lazy-load + code splitting | 500 - 1,200 | 4 - 8 days |
| CDN + cache setup | 400 - 900 | 2 - 4 days |
| Reduce render-blocking JS/CSS | 300 - 900 | 2 - 5 days |
| Post-optimization monitoring | 300 - 600 | 30 days |
Realistic total budget to fix a slow site: 2,400 to 6,500 EUR, often paid back in under two quarters thanks to conversion gains.
Before / after: PageSpeed and SEO impact
Here is a typical 2026 transformation for a B2B business site initially scoring 38/100 on mobile.
| Metric | Before | After | Google target |
|---|---|---|---|
| Mobile PageSpeed score | 38 | 91 | > 90 |
| LCP | 4.2 s | 2.1 s | < 2.5 s |
| INP | 340 ms | 150 ms | < 200 ms |
| CLS | 0.28 | 0.05 | < 0.1 |
| Bounce rate | 61 % | 44 % | - |
| Conversion rate | 1.4 % | 2.3 % | - |
Improving Core Web Vitals pulls two levers at once: SEO ranking (an official Google ranking signal) and direct conversion rate.
Mini case study
Sophie, e-marketing lead at a software vendor in Miami, runs a site receiving 12,000 visits/month at a 1.4 % conversion rate, i.e. 168 leads/month. She invests 4,500 EUR in an audit plus optimizations. LCP drops from 4.2 s to 2.1 s and conversion climbs to 2.3 %, i.e. 276 leads/month, +108 leads. At an average value of 35 EUR/lead, that's 3,780 EUR/month of added value: the investment is recovered in 35 days.
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FAQ
How much does a standalone Core Web Vitals audit cost?
Between 900 and 2,500 EUR in 2026 depending on site size. It includes the LCP/INP/CLS diagnosis, a prioritized report, and a costed action plan.
How quickly do the gains show?
Technical optimizations take 2 to 4 weeks. The conversion effect is immediate after launch; the SEO effect materializes over 4 to 8 weeks.
What concrete conversion gain should I expect?
As a 2026 rule of thumb, each second cut from LCP improves conversion by about 7 %. Going from 4.2 s to 2.1 s can add 40 to 60 % relative conversion.
Do I need to rebuild the whole site?
Rarely. 80 % of the gains come from images, cache, CDN, and JS. A full rebuild is only justified if the technical foundation is obsolete.
Do these gains last?
Yes, if you avoid piling on third-party scripts and heavy plugins. A quarterly check at 300-600 EUR is enough to maintain the scores.
Let's scope your project. Send us your site URL and current PageSpeed score, and we'll price an audit + optimization plan (2,400 to 6,500 EUR) deliverable in 2 to 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.
