The verdict in three sentences
A Core Web Vitals audit pinpoints exactly why your B2B site is slow and what it costs you in SEO and conversion. The full project (audit + optimization) runs $4,000 to $14,000 over 3 to 6 weeks, depending on technical debt and CMS. Typical gains: LCP halved, bounce rate -20%, and unlocked Google positions previously capped by slowness.
Audit line items and their cost
2026 Core Web Vitals rest on three metrics: LCP (loading of the largest visible element, target < 2.5s), INP (responsiveness to interactions, target < 200ms), and CLS (visual stability, target < 0.1). A serious audit measures these in field data (CrUX) and in the lab, then prices each fix.
| Line item | Common problem | Optimization cost | Expected gain |
|---|---|---|---|
| LCP (hero image) | Unoptimized image, no preload | $900-3,000 | -1 to -2s |
| INP (JavaScript) | Blocking third-party scripts | $1,200-4,000 | -150 to -400ms |
| CLS (layout) | Images without dimensions, ads | $600-1,800 | CLS < 0.1 |
| Images & media | No WebP/AVIF, no lazy load | $700-2,400 | -40% weight |
| Cache & CDN | No cache, distant server | $600-2,100 | TTFB -50% |
| Code & rendering | Unminified CSS/JS, no SSR | $1,200-3,500 | Variable |
Prioritization matters as much as the list: start with high impact-to-cost fixes, often images and caching.
Impact on ranking and conversion
Performance is not just an SEO signal: it is a conversion multiplier. Here are 2026 orders of magnitude observed after optimizing a B2B site.
| Metric | Before audit | After optimization | Business effect |
|---|---|---|---|
| LCP | 4.1s | 2.2s | Better mobile ranking |
| INP | 380ms | 170ms | Smooth navigation |
| CLS | 0.24 | 0.05 | Fewer mis-clicks |
| Bounce rate | 58% | 46% | About -20% |
| Pages/session | 2.1 | 2.8 | +33% |
| Form conversion rate | 2.3% | 3.0% | +30% |
One second saved on mobile load regularly translates into several conversion points on quote-request forms.
Targeted optimization or full technical rebuild?
| Criterion | Targeted optimization | Full technical rebuild |
|---|---|---|
| Budget | $4,000-14,000 | $30,000-70,000 |
| Timeline | 3-6 weeks | 3-5 months |
| SEO risk | Low | Medium (must be managed) |
| Fit when | Moderate debt, sound base | Obsolete CMS, heavy debt |
| Gain duration | 12-24 months | 4-6 years |
| Reversibility | High | Low |
If your technical foundation is healthy, targeted optimization offers the best ratio. Beyond a certain debt level (old CMS, spaghetti code), a rebuild becomes more cost-effective in the medium term.
Mini case study
Need a professional website?
Kolonell builds websites that attract clients, optimized for the Sénégalese market. Free quote in 2 minutes.
Sarah, COO of a logistics firm in Rotterdam, commissions an audit + optimization at $8,500. Her B2B site gets 45,000 visits/month at a 2.3% form conversion rate, i.e. 1,035 leads/month. After optimization the rate reaches 3.0%, i.e. 1,350 leads/month: +315 leads. With an alternative acquisition cost (Ads) of $40/lead, those extra leads are worth $12,600/month. The investment pays back in under three weeks of operation.
FAQ
Which tools do you use for the audit?
PageSpeed Insights and CrUX for field data, Lighthouse and WebPageTest in the lab, plus JavaScript load profiling. We cross real and synthetic data so we don't optimize blindly.
How long to see the SEO effect?
Google recalculates field signals over a rolling 28-day window. Plan 4 to 8 weeks after deployment for positions to move, faster on mobile.
Has INP really become critical?
Yes. Since it replaced FID, INP penalizes sites loaded with third-party scripts (chat, analytics, tags). It is often the hardest item to fix.
Can a WordPress site hit the targets?
Yes, with a light theme, good hosting, server cache, and plugin cleanup. Many slow WordPress sites are slow because of superfluous extensions, not the CMS itself.
Should the audit be repeated afterward?
A 30-day check validates gains in field data, then a quarterly review is enough to prevent regression from newly added features or scripts.
Let's scope your project. Send us your URL, CMS, and current scores: we'll frame an audit + optimization ($4,000-14,000) with impact-based prioritization and a 3- to 6-week timeline. 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.
