The verdict in three sentences
A performance budget is a quantified limit (LCP, INP, CLS, page weight) that every new feature must respect, or be blocked. Without it, a site that is fast at launch becomes slow within six months, one marketing script and unoptimized image at a time. The 2026 thresholds to hold: LCP < 2.5 s, INP < 200 ms, CLS < 0.1, with a weight ceiling and an automatic alert in continuous integration (CI).
The 2026 Core Web Vitals thresholds
Google classes each metric as "good", "needs improvement" and "poor". Here are the reference thresholds and their business impact.
| Metric | Good | Needs improvement | Poor | What it measures |
|---|---|---|---|---|
| LCP | < 2.5 s | 2.5 - 4 s | > 4 s | Speed to display main content |
| INP | < 200 ms | 200 - 500 ms | > 500 ms | Responsiveness to clicks/input |
| CLS | < 0.1 | 0.1 - 0.25 | > 0.25 | Visual stability (no jump) |
| TTFB | < 0.8 s | 0.8 - 1.8 s | > 1.8 s | Server response time |
In the Senegalese market, these thresholds must be met on mobile over 4G or even 3G, not just fiber. A site that scores green in the lab but loads in 5 s on an entry-level smartphone fails in real life.
The weight budget to set
Core Web Vitals largely derive from weight and request count. Set ceilings per page.
| Resource | Recommended budget | Hard limit | Main lever |
|---|---|---|---|
| JavaScript | < 150 KB | 200 KB | code splitting, drop libraries |
| Images (page total) | < 400 KB | 500 KB | WebP/AVIF, lazy loading |
| CSS | < 60 KB | 100 KB | purge unused classes |
| Web fonts | < 100 KB | 150 KB | 2 weights max, woff2 |
| HTTP requests | < 35 | 50 | bundling, fewer third parties |
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The conversion impact is direct: field studies show roughly +1 s of LCP = -7% of conversions. On a shop doing 2,000,000 FCFA/month, gaining 1.5 s can mean 200,000 to 250,000 FCFA recovered monthly.
Mini case study
Moussa runs a classifieds site in Thies. His mobile LCP is 4.3 s, INP 380 ms, JS weight 620 KB (three analytics tools + a third-party chat). Traffic: 40,000 visits/month, conversion rate 2.1%. After an enforced performance budget (JS down to 180 KB, AVIF images, a single analytics tool), LCP drops to 1.9 s and conversion rises to 2.6%. On 40,000 visits, that is 200 extra conversions per month. Optimization cost: 650,000 FCFA, paid back within months.
FAQ
How often should I measure? Continuously: an automatic test (Lighthouse CI) on each deployment blocks any regression, plus a monthly field check via Search Console (real CrUX user data).
Which free tools should I use? PageSpeed Insights and Search Console for real data, Lighthouse for diagnosis, WebPageTest to simulate Senegalese 3G. All free.
Does CLS really matter? Yes: a CLS above 0.25 makes content jump during loading, causes accidental clicks and drives visitors away. It is often caused by images without dimensions or banners injected late.
Does a good score guarantee better Google ranking? Not alone: Core Web Vitals are one factor among many, but they break ties between pages with equivalent content and above all improve conversion rate, which matters as much as rank.
Let's talk about your project. We measure your real Core Web Vitals and define a performance budget together, with automatic alerts. 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.
