The verdict in three sentences
Speed is not a technical detail, it is a direct revenue variable: a site that takes 5 seconds to display can lose half its conversions compared with one that loads in 2 seconds. On mobile, where most African traffic happens, every 100 ms saved is worth 1 to 2 % more conversion. Worse, a slow site burns your advertising budget: you pay for the Meta Ads click, but the visitor leaves before the page even appears.
The conversion / load-time curve
The table links LCP to relative conversion rate, using 1-2 s as base 100 (2026 order of magnitude, mobile e-commerce).
| LCP (load) | Relative conversion | Loss vs base | Mobile bounce rate |
|---|---|---|---|
| 1-2 s | 100 % (base) | — | ~28 % |
| 3 s | ~80 % | -20 % | ~38 % |
| 4 s | ~65 % | -35 % | ~50 % |
| 5 s | ~50 % | -50 % | ~60 % |
| 6 s+ | ~38 % | -62 % | ~68 % |
Speed and ad cost: the hidden waste
A slow site loses more than organic sales; it inflates the cost per acquisition on paid campaigns. Here are two scenarios for the same 300,000 FCFA Meta Ads budget (order of magnitude).
| Metric | Slow site (LCP 5 s) | Fast site (LCP 2 s) |
|---|---|---|
| Meta Ads budget | 300,000 FCFA | 300,000 FCFA |
| Clicks received | 1,500 | 1,500 |
| Visitors who stayed (post-load) | 600 | 1,080 |
| Conversion rate | 1.2 % | 2.4 % |
| Sales generated | 7 | 26 |
| Cost per sale | 42,900 FCFA | 11,500 FCFA |
The 2026 Core Web Vitals targets
Google evaluates three metrics to judge the loading experience. Meeting them improves both conversion and ranking.
| Metric | "Good" target | What it measures |
|---|---|---|
| LCP | < 2.5 s | Render of the largest visible element |
| INP | < 200 ms | Responsiveness to interactions |
| CLS | < 0.1 | Visual stability (no jump) |
Mini case study
Awa runs an online cosmetics shop in Dakar. Her site loaded in 4.6 s (LCP), with a 1.1 % mobile conversion rate. After optimization (WebP images, reduced JavaScript, preloaded hero image), LCP falls to 2.1 s and conversion rises to 2.0 %. On her 4,500 monthly visitors, orders go from 50 to 90 per month. At an average ticket of 22,000 FCFA, those 40 extra sales represent 880,000 FCFA of additional monthly revenue — for a one-off optimization job.
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FAQ
Does every second really matter that much?
Yes. Field studies converge: going from 1 s to 3 s of load time drops conversion by around 20 %, and from 1 s to 5 s by nearly 50 %. The effect is even stronger on mobile and slow connections, typical of the African market.
What is INP and why did it replace FID?
INP (Interaction to Next Paint) measures the page's responsiveness to all interactions, not just the first. It became an official Core Web Vital because it better reflects real experience: aiming under 200 ms ensures a page that responds quickly to taps.
Can a slow site ruin a Meta Ads campaign?
Absolutely. If the page takes 5 s to load, a large share of paid clicks leave before display: you pay for traffic without converting it. Speeding up the site can cut cost per acquisition by two to three times without touching the budget.
Does CLS really affect sales?
Yes, indirectly. A high CLS (content jumping during load) causes accidental clicks and frustration, especially at checkout. Keeping it under 0.1 reduces cart abandonment tied to visual instability.
Where do I start to improve conversion through speed?
Start with LCP: optimize the main image or element shown on load (compression, preloading). It is often the best effort-to-gain lever, even before touching JavaScript or fonts.
Let's talk about your project. We measure your real speed and turn it into conversion points. 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.
