The verdict in three sentences
In West Africa, over 80% of e-commerce traffic is mobile, often on 3G of 3 to 8 Mbps with high latency. Each extra second of load costs about 7% of conversion, and every MB eats into the buyer's limited data bundle. A PWA (Progressive Web App) with a service worker brings repeat-visit load under 1 second and works even offline: it's the only realistic design for this market.
The techniques that make the difference
Optimizing for 3G isn't about beautifying, it's about removing weight and caching. Each technique has a measurable gain in bytes saved and conversion recovered.
| Technique | Data saved | Load impact | Conversion impact |
|---|---|---|---|
| AVIF / WebP images | 30 to 50% of bytes | -1 to -3 s | +5 to +10% |
| Service worker (PWA cache) | ~90% on repeat visit | < 1 s on return | +8 to +15% |
| Lazy loading images | 20 to 40% on first screen | -0.5 to -2 s | +3 to +7% |
| Code splitting / smaller bundle | 15 to 30% of JS | -0.5 to -1.5 s | +3 to +6% |
| System fonts / preload | 50 to 200 KB | -0.3 to -0.8 s | +2 to +4% |
| Offline mode | N/A | Browsing without network | +5 to +10% |
The service worker is the most powerful lever: it caches the store's shell, so on the second visit the customer sees the catalogue instantly, even in a lift or a poorly covered village.
Data cost, an invisible barrier
Many West African buyers browse on bundles of 500 MB to 1 GB. A heavy 8 MB-per-page store burns their bundle and drives them away before they even buy. Going lighter respects the customer's wallet.
| Page weight | Data used / visit | Load on 3G (5 Mbps) | Verdict |
|---|---|---|---|
| 8 MB (unoptimized) | 8 MB | 12 to 18 s | Near-certain abandonment |
| 3 MB (partly optimized) | 3 MB | 5 to 8 s | Significant drop-off |
| 1 MB (optimized) | 1 MB | 2 to 3 s | Acceptable |
| < 500 KB (cached PWA) | ~50 KB on return | < 1 s | Ideal |
Add-to-homescreen and push notifications turn the PWA into a near-app, without the weight of a store download or the associated fees.
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Mini case study
Seynabou sells natural cosmetics online. Her unoptimized store weighs 7 MB per page; on 3G it loads in 15 seconds. Her pre-load abandonment rate is 55%, and her overall conversion rate 1.2%.
She switches to a PWA: AVIF images, service worker, lazy loading. The page drops to 900 KB, then to 50 KB on repeat visits thanks to caching. Load falls to 2 seconds, then under 1 second. Pre-load abandonment drops to 18% and conversion climbs to 2.3%. On 5,000 visits/month and a 15,000 FCFA basket, she goes from 60 to 115 sales: +825,000 FCFA/month for the same traffic, purely from performance.
FAQ
Why a PWA rather than a native app? A PWA offers offline caching, add-to-homescreen and push notifications with no store download or 15-30% fees. On African 3G, it brings repeat-visit load under 1 second.
What real impact does speed have on sales? Each extra second of load costs about 7% of conversion. Going from 15 s to under 2 s can nearly double the conversion rate, as in our case study.
How do I reduce image weight? AVIF and WebP formats save 30 to 50% of bytes with no visible loss, and lazy loading avoids loading what isn't on screen yet. Together they save several seconds on 3G.
Is offline mode really useful in e-commerce? Yes: the customer can browse the cached catalogue with no network, in transit or a poorly covered zone, then check out as soon as connectivity returns. This adds 5 to 10% conversion.
How much data does an optimized store use? An optimized PWA loads about 1 MB on the first visit and only ~50 KB on return thanks to caching. Against 500 MB to 1 GB bundles, that's decisive to keep the buyer from leaving.
Let's talk about your project. We build your store as a 3G-optimized PWA, with offline caching, AVIF images and mobile-money payment. 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.
