The verdict in three sentences
A slow site does not only hurt SEO: it directly destroys revenue by inflating bounce rate and breaking the conversion funnel. In 2026, performance optimization in Amsterdam costs from EUR 1,000 (audit + quick wins) to EUR 16,000 (targeted front refactor), with no full rebuild. The ROI is one of the fastest on the web: +8 to +20 % conversions for a contained cost.
How much does slowness really cost
| Load time | Estimated bounce rate | Conversion impact (order of magnitude) |
|---|---|---|
| 1 s | ~9 % | Baseline |
| 2 s | ~13 % | -4 to -7 % |
| 3 s | ~24 % | -10 to -20 % |
| 4 s | ~38 % | -25 to -40 % |
| 5 s+ | ~50 %+ | -40 % and more |
On mobile and degraded connections the effect is amplified. Every tenth of a second saved on TTFB and LCP reads directly in the purchase or contact funnel.
2026 price grid (Amsterdam, no full rebuild)
| Service | 2026 range (EUR) | Timeline | Target gain |
|---|---|---|---|
| Audit + quick wins | 1,000 – 2,800 | 1 wk | TTFB -0.3 s |
| Image/cache/CDN optimization | 3,000 – 9,000 | 2-3 wks | LCP -1.5 s |
| Targeted front refactor (JS, hydration) | 5,000 – 16,000 | 3-5 wks | INP < 200 ms |
| Performance maintenance | 150 – 500 /mo | ongoing | Maintain |
Overall timeline: 3 to 6 weeks. We typically target +0.5 s TTFB and +8 to 20 % conversions depending on the starting point.
Mini case study
Sarah, COO of a logistics firm in Amsterdam, sees a 58 % bounce rate and a slow-loading quote form (LCP at 3.8 s). Her site generates 320 quote requests/month at a 1.9 % conversion rate. She commissions an optimization at EUR 7,500 (AVIF images, cache, CDN, JS trimming) over 4 weeks. Target: LCP at 2.2 s, conversions +14 %, i.e. +45 requests/month. With an average signed deal of EUR 4,200 and a 12 % close rate, that is ~EUR 270,000 additional annual revenue. The investment pays back in under a month.
FAQ
Need a professional website?
Kolonell builds websites that attract clients, optimized for the Sénégalese market. Free quote in 2 minutes.
Optimization or full rebuild?
If the architecture is sound, optimization (EUR 3,000-16,000) is enough and avoids a heavy project. A rebuild is only justified if the CMS or theme structurally throttles performance. An audit at EUR 1,000-2,800 settles the question.
How long before conversions improve?
Immediately for user experience, and over 4-8 weeks for field metrics (CrUX) and SEO. The conversion effect shows in analytics almost instantly.
What are the most cost-effective quick wins?
Image compression and the right format (AVIF), browser/CDN caching, lazy-load and removing unused JavaScript. These actions at EUR 1,000-2,800 often deliver 70 % of the gain for 30 % of the budget.
Is a CDN essential?
For international or mobile traffic, yes. A CDN (Cloudflare, Vercel) cuts latency by serving assets from a point of presence near the user, improving TTFB and LCP everywhere.
Can you guarantee a conversion gain?
No serious provider guarantees an exact figure, since conversion also depends on offer and content. However, we guarantee measurable technical targets (LCP, TTFB, INP) that historically lift conversion.
Let's scope your project. Send us the URL, your speed metrics and current conversion volume. Audit + quick wins from EUR 1,000. 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.
