The verdict in three sentences
Core Web Vitals are no longer a gimmick: since Google replaced FID with INP (Interaction to Next Paint), a slow B2B site loses rankings and, above all, conversions. Turning the three metrics green — INP < 200 ms, LCP < 2.5 s, CLS < 0.1 — costs 3,000 to 9,000 EUR depending on technical debt, over 3 to 6 weeks. The real prize is not the score: it is the -22 % bounce rate and +12 % form conversions that speed unlocks.
The three metrics and their 2026 thresholds
Google assesses each metric at the 75th percentile of real visits (CrUX data). A "green" site must hold the thresholds on mobile, where most B2B traffic sits in 2026.
| Metric | What it measures | Good threshold | Needs fixing |
|---|---|---|---|
| LCP | Largest element render | < 2.5 s | > 4.0 s |
| INP | Interaction responsiveness | < 200 ms | > 500 ms |
| CLS | Visual stability | < 0.1 | > 0.25 |
| TTFB | Server response | < 800 ms | > 1.8 s |
| JS weight | JavaScript executed | < 300 KB | > 1 MB |
What costs what: the work breakdown
Not all levers are equal. Images and third-party JS alone explain 60 to 70 % of poor B2B scores. Here is an indicative 2026 cost per lever.
| Optimisation lever | Main effect | 2026 cost | Typical gain |
|---|---|---|---|
| AVIF/WebP images + lazy-loading | LCP | 600-1,500 EUR | -1 to -2 s LCP |
| Third-party JS reduction (tags, chat) | INP | 800-2,500 EUR | -150 to -300 ms INP |
| Space reservation (CLS) | CLS | 400-1,000 EUR | CLS < 0.1 |
| Edge hosting / CDN | TTFB | 1,000-2,500 EUR setup + 50-200 EUR/mo | -400 to -900 ms TTFB |
| Critical CSS + preloading | LCP/render | 800-2,000 EUR | -0.5 to -1.2 s |
Budget a full project at 3,000 to 9,000 EUR; sites built on overloaded multi-plugin themes push to the top of the range.
Mini case study
Bram, digital director at an Amsterdam B2B firm (industrial software vendor, 60 pages), fails the CWV report: mobile LCP at 3.8 s, INP at 420 ms. He commissions a 6,200 EUR project over 5 weeks: switch to AVIF, removal of two redundant marketing tags, migration to edge hosting and critical CSS. Result: LCP at 1.4 s, INP at 180 ms, mobile bounce rate from 61 % to 47 % (-22 %) and form conversions from 1.8 % to 2.0 % (+12 %). On 9,000 mobile visits/month, that is ~18 extra leads/month; at 700 EUR lead value, the project pays back in about 6 weeks.
FAQ
Need a professional website?
Kolonell builds websites that attract clients, optimized for the Sénégalese market. Free quote in 2 minutes.
Is INP harder to optimise than LCP?
Often yes: INP depends on JavaScript executed during interactions (menus, filters, forms). Reducing third-party JS and breaking up long tasks usually pushes INP under 200 ms in 2 to 4 weeks.
Does a good CWV score guarantee better rankings?
No, it is one factor among hundreds. But with equal content, speed is the tiebreaker, and above all it directly lifts conversion rate regardless of ranking.
What does maintaining the scores cost over time?
A monthly follow-up of 150 to 400 EUR (CrUX monitoring, regression alerts) prevents new tags or visuals from turning the site red again.
Do I need to change host to improve TTFB?
Not always. An edge CDN in front of the current host is often enough to bring TTFB under 800 ms for 50 to 200 EUR/month, without a heavy migration.
How fast does Google account for the improvements?
Since CrUX data is a rolling 28-day window, expect 4 to 6 weeks after deployment for the report to officially turn green.
Let's scope your project. Send us your URL and current CWV report; we identify priority levers and price the path to green. 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.
