The verdict in three sentences
Core Web Vitals are the three speed scores Google uses to rank: LCP under 2.5 s, INP under 200 ms, CLS under 0.1. In Senegal, on 3G/4G, many sites exceed 4 s of LCP because of heavy images and unoptimized JavaScript. By moving to WebP/AVIF images (-60 % weight), lazy loading and a CDN, you hit the targets and cut bounce by about 20 %.
Target metrics versus the Senegalese reality
| Metric | Google target | Common in Senegal | Main lever |
|---|---|---|---|
| LCP (loading) | < 2.5 s | 3.5 - 6 s | Images, hosting, CDN |
| INP (responsiveness) | < 200 ms | 250 - 500 ms | Reduce JavaScript |
| CLS (stability) | < 0.1 | 0.15 - 0.3 | Image/font dimensions |
| Total page weight | < 1.5 MB | 3 - 6 MB | Compression, modern formats |
| Mobile Lighthouse score | > 90 | 40 - 70 | All levers combined |
The "common" column is a 2026 estimate from typical audits of unoptimized local showcase and e-commerce sites.
Prioritized optimization plan
| Priority | Action | Expected gain | Effort |
|---|---|---|---|
| 1 | Convert images to WebP/AVIF | -50 to -60 % weight | Low |
| 2 | Lazy load images and iframes | -20 to -30 % LCP | Low |
| 3 | CDN + browser cache | -200 to -800 ms LCP | Medium |
| 4 | Reduce/defer JavaScript | -100 to -300 ms INP | Medium |
| 5 | Preload fonts + font-display swap | -0.05 to -0.1 CLS | Low |
| 6 | Size images and ads | CLS near 0 | Low |
Always start with images: on a typical Senegalese site they make up 50 to 70 % of page weight.
Why speed pays
- Google has used Core Web Vitals as a ranking signal since 2021; a fast site climbs.
- Moving LCP from 5 s to 2 s cuts the bounce rate by about 20 %.
- On 3G, every megabyte saved means several seconds gained and data preserved for the user.
- More page views per session and a better conversion rate, especially in e-commerce.
Mini case study
Fatou, who runs an e-commerce site for wax fabrics in Thies, has a 5.4 s LCP and a mobile Lighthouse score of 48. Her catalog holds 120 JPEG images averaging 800 KB. After converting to WebP (average weight 280 KB, i.e. -65 %), lazy loading and a CDN, the LCP drops to 2.1 s and the score climbs to 92. Bounce falls from 58 % to 46 %. On 6,000 visits/month, that is about 720 more engaged sessions; at 1.8 % conversion and a 22,000 FCFA basket, roughly 285,000 FCFA in added monthly sales.
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FAQ
What is a good Core Web Vitals score?
LCP under 2.5 s, INP under 200 ms, CLS under 0.1. Below these thresholds on mobile, Google treats your page as fast and favors it.
Are images really the first problem?
Yes: on a typical local site they account for 50 to 70 % of the page. Converting them to WebP/AVIF often cuts 50 to 60 % in a single operation.
How long to optimize an existing site?
One optimization pass (images, lazy loading, CDN) usually takes 3 to 7 days depending on catalog size, with no full redesign.
Is a CDN useful in Senegal?
Yes, it brings files closer to the user and cuts LCP by 200 to 800 ms, especially for visitors outside Dakar or in the diaspora.
How do I measure my Core Web Vitals?
PageSpeed Insights and Lighthouse provide all three metrics for free. Target the "mobile" values since most Senegalese traffic is on smartphones.
Let's talk about your project. We audit your Core Web Vitals and apply a costed optimization plan. 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.