Why your website is slow (and why it costs you money)
A slow website in 2026 means losing 7% to 22% of possible revenue. Amazon measures -1% revenue per 100 ms of added latency. Across the 60 performance audits Kolonell ran between January 2025 and April 2026 (SMEs in Senegal, Ivory Coast, France), the pattern is identical: 10 root causes recur every time, in varying proportions. Here is what they are and how to fix them.
The 10 causes — diagnosis and fix
1. Unoptimized images (present in 92% of audits)
Symptom: LCP > 3s. JPEG/PNG images 800 KB to 4 MB served full-screen.
Fix: switch to WebP/AVIF with next/image (60-85% weight saving). Serve adaptive sizes (srcset). Native lazy loading. Median LCP gain: -1.2s.
2. Cheap / shared hosting (78% of audits)
Symptom: TTFB > 1.5s. Server in France/USA serving Dakar traffic (network latency).
Fix: Vercel (global edge) or DigitalOcean Frankfurt + Cloudflare CDN. Budget: 0-30,000 FCFA/month. TTFB gain: 1500ms → 150ms.
3. Too many WordPress plugins (84% of WP audits)
Symptom: 20-50 active plugins, 2-5 MB JS bundle, 8-15s admin latency.
Fix: audit each plugin (Query Monitor). Disable all non-critical. Target 8-15 plugins max. Or redesign to Next.js (see dedicated article).
4. Unoptimized application code (67% of custom audits)
Symptom: INP > 400ms. React renders that re-render the whole tree, 1.5 MB bundles, JS blocking the main thread.
Fix: code splitting (next/dynamic), React memoization, remove unused NPM dependencies. INP gain: 50-70%.
5. No caching (or misconfigured cache) (71% of audits)
Symptom: every visit reloads everything. Cache-control headers missing or no-cache.
Fix: Cache-Control: public, max-age=31536000, immutable on static assets. s-maxage + stale-while-revalidate on APIs. ISR on dynamic pages.
6. No CDN (63% of audits)
Symptom: everything served from one origin. Visitors outside the geographic zone → load times ×3.
Fix: Cloudflare (free is enough), Vercel Edge (built-in), Bunny.net (8,000 FCFA/month). TTFB gain: 60-80% for distant visitors.
7. Render-blocking JavaScript (89% of audits)
Symptom: Total Blocking Time > 600ms. Third-party scripts (GTM, Hotjar, chat widget) loaded synchronously.
Fix: