The verdict in three sentences
A low Lighthouse score translates directly into a high bounce rate and lost sales. Targeting a 90+ score with INP < 200 ms and CLS < 0.1 costs, in 2026, between 2,800 and 6,000 EUR (audit + work), over a 3 to 6 week timeline. The golden rule stays relentless: -1 s of load time = +7% conversion.
What Lighthouse really measures in 2026
The Lighthouse score (0-100) aggregates performance, accessibility, best practices and SEO. On the performance side, field Core Web Vitals (INP, LCP, CLS) outweigh the lab score. A sales director must tell the two apart: a 'lab' score of 95 does not guarantee good real-world vitals if hosting or the user network are poor.
| Indicator | Green threshold 2026 | What degrades it |
|---|---|---|
| Overall Lighthouse score | >= 90 | Heavy JS, unoptimised images |
| LCP | < 2.5 s | Uncompressed hero images |
| INP | < 200 ms | Third-party scripts, slow hydration |
| CLS | < 0.1 | Ads, fonts without dimensions |
| Time to Interactive | < 3.8 s | JS bundle > 300 KB |
| Total weight | < 1.5 MB | Auto-play videos, sliders |
Performance pricing grid in Berlin for 2026
Prices vary with site complexity (CMS, e-commerce, custom) and the starting point. Here are 2026 orders of magnitude for a Berlin B2B SME, with a vendor day rate of 480 to 620 EUR.
| Service | Price 2026 (EUR) | Timeline | Expected effect |
|---|---|---|---|
| Lighthouse + CWV audit | 800 - 1,500 | 3 - 5 d | Prioritised diagnosis |
| Image/font optimisation | 700 - 1,400 | 1 wk | -40 to -60% weight |
| JS / bundle refactor | 1,000 - 2,200 | 1 - 2 wks | INP < 200 ms |
| Hosting + CDN + cache | 300 - 900 | 3 - 5 d | LCP -1 to -2 s |
| Performance maintenance | 200 - 400/mo | ongoing | Score kept 90+ |
The full images/JS/hosting work sits between 2,000 and 4,500 EUR, on top of the initial audit. The overall 3 to 6 week timeline depends mostly on access availability (host, CMS) and mock-up sign-off.
Mini case study
Sophie, sales director at an industrial software vendor in Berlin, saw her mobile bounce rate climb to 68%. The site loaded in 5.1 s. Investment: 1,200 EUR audit + 3,400 EUR of work (images, JS bundle, CDN). Result in 5 weeks: load at 2.3 s (i.e. -2.8 s), Lighthouse score from 58 to 92, INP at 170 ms. Applying the -1 s = +7% rule: +2.8 s fixed, roughly +19% conversion. On 3,000 visitors/month and an initial 2.4% rate (72 demo requests), that means +14 qualified requests/month. With an average contract of 9,000 EUR and 15% close rate, the 4,600 EUR investment pays back in the first month.
FAQ
Need a professional website?
Kolonell builds websites that attract clients, optimized for the Sénégalese market. Free quote in 2 minutes.
Does a good Lighthouse score guarantee good SEO?
Not on its own, but it is a factor. Google uses field vitals (CrUX data) as a ranking signal. A 90+ lab score paired with good real vitals improves both rankings and conversion.
Why does my score vary on every test?
Lighthouse in lab mode simulates a network and device; variations come from third-party scripts, caching and server load. Rely on the average of several tests and 28-day field data.
How much does it cost to maintain performance over time?
A performance maintenance plan of 200 to 400 EUR/month suffices for most SMEs: it watches for regressions after each content or plugin update.
Has INP replaced FID?
Yes, since March 2024 INP is the official responsiveness vital. Target: < 200 ms. It mainly penalises sites heavy on JavaScript and third-party scripts.
Do we need a CDN for a German-only audience?
Often yes: a CDN cuts latency, offloads the origin server and improves LCP even domestically. The gain is clear as soon as you have traffic spikes or heavy images.
Let's scope your project. Send us your site URL and current scores: we'll price the audit and performance work to target a Lighthouse 90+ within 6 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.
