The verdict in three sentences
A B2B website with 70% of URLs rated "poor" in Search Console loses both rankings and demo requests. The typical 2026 project costs 4,200 to 11,500 EUR in total (about 3,600 to 9,900 GBP): an audit at 1,200 to 2,500 EUR, then fixes at 3,000 to 9,000 EUR targeting images, third-party scripts, fonts and caching. The targets to put in the contract are LCP under 2.5 s, INP under 200 ms and CLS under 0.1 on field data, with an observed conversion uplift of 8 to 15%.
Thresholds, diagnostics and common causes
Google assesses Core Web Vitals on real Chrome user data, at the 75th percentile, over a rolling 28 days. A lab Lighthouse score of 95 is not enough if real users, often on mobile and 4G, have a different experience. On the B2B sites we audit, the causes are almost always the same.
| Metric | Good | Poor | Common cause on a B2B site | Typical fix |
|---|---|---|---|---|
| LCP (main content render) | 2.5 s or less | Over 4 s | 1.5 MB JPEG hero image | AVIF, preload, fixed dimensions |
| INP (interaction responsiveness) | 200 ms or less | Over 500 ms | Chat, CRM, tag manager, A/B testing loaded at start | Deferred loading, splitting long tasks |
| CLS (visual stability) | 0.1 or less | Over 0.25 | Cookie banner, web fonts, dynamic inserts | Reserved space, font-display, fixed height |
| TTFB (server response) | 0.8 s or less | Over 1.8 s | Shared hosting, no caching | CDN, page cache, static rendering |
| Mobile page weight | Under 1.5 MB | Over 4 MB | Videos, carousels, 6 fonts | Compression, font subsetting |
| Third-party scripts | Fewer than 8 | More than 20 | Pile-up of marketing tools | Inventory and removal |
For a software vendor, INP is most often the culprit: a chat widget, a session recording tool and three ad pixels are enough to block the main thread for more than 400 ms.
Typical quote: audit, then fixes
We recommend separating the audit from the fixes. The audit produces a prioritised, priced and measurable list. Fixes are then committed batch by batch, with before and after measurement. Amounts are 2026 orders of magnitude for a 50 to 300 page site.
| Batch | Content | Budget excl. VAT | Timeline |
|---|---|---|---|
| Audit | CrUX field data, 10 templates analysed, prioritised plan | 1,200 to 2,500 EUR | 1 to 2 weeks |
| Images | AVIF/WebP conversion, responsive sizes, lazy loading | 800 to 2,000 EUR | 3 to 5 days |
| Third-party scripts | Inventory, deferred loading, facades for chat and video | 1,000 to 3,000 EUR | 4 to 8 days |
| Fonts and CSS | Subsetting, preload, critical CSS | 500 to 1,500 EUR | 2 to 4 days |
| Cache and CDN | CDN setup, page cache, Brotli compression | 700 to 2,500 EUR | 2 to 5 days |
| Total fixes | All batches | 3,000 to 9,000 EUR | 3 to 6 weeks |
| Monitoring | Monthly dashboard, regression alerts | 100 to 300 EUR per month | Ongoing |
Allow 28 days after release for field data to switch to "good" in Search Console. The gain is then measured on conversion, not only on rankings.
Mini case study
Sarah, marketing manager at a business software vendor in London, finds that 70% of her URLs are rated "poor", with a mobile INP of 480 ms. The site gets 12,000 visits per month and converts 1.5% of visitors into demo requests, or 180 requests. After a 1,800 EUR audit and 6,500 EUR of fixes, INP drops to 160 ms and LCP to 2.1 s. With a 12% conversion uplift, the site produces about 202 requests, 22 more per month. At an 8% close rate and an average annual contract of 6,000 EUR, that is an estimated 10,560 EUR of new annual contract value signed each month. The 8,300 EUR project pays for itself in the first month of results.
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FAQ
How much does a Core Web Vitals audit cost for a B2B website?
Between 1,200 and 2,500 EUR for a 50 to 300 page site, with 10 templates analysed and a prioritised plan. An audit under 500 EUR is often just an automated Lighthouse report.
How long before the improvement shows in Search Console?
About 28 days after release, because Google uses field data over a rolling 28 days. Lab tests show the gain from day one.
What conversion uplift should we expect?
On B2B sites, we usually observe 8 to 15% more conversions when all three metrics turn "good". The gain is larger on mobile, where speed gaps are widest.
Do we need to rebuild the site to fix INP?
Rarely: in 7 cases out of 10, a third-party script inventory and deferred loading are enough. A rebuild is justified if the theme or page builder ships more than 3 MB of JavaScript.
How do we stop performance degrading after the fixes?
Set up monthly monitoring at 100 to 300 EUR with alerts, and an internal rule: every new marketing script goes through technical approval. Without it, gains erode within 6 to 12 months.
Let's scope your project. Send us your site URL and a screenshot of your Core Web Vitals report: we will price the audit and fix batches, with committed LCP and INP targets and a timeline in 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.
