Performance services
Performance services
Three layers of perf observability, deliberately split across tools because no single free tier covers all three:
- Real-User Monitoring (RUM, client-side Web Vitals) — Vercel Speed Insights. Free, runs on any host. Captures real users on real devices.
- Server-side / edge-measured perf — Cloudflare Web Analytics (already in use for analytics). Free, unlimited, no script.
- Performance traces (API + Worker timing) — Sentry Performance. Sampled traces in the same dashboard as errors.
| Service | Status | One-line role |
|---|---|---|
| vercel-speed-insights.md | active | RUM Web Vitals on every site — free, no Vercel hosting required |
Why all three?
- Cloudflare Web Vitals is server-side, measured at the edge — it tells us what the network and CDN delivered, not what the user saw. Misses CLS entirely (CLS only happens after paint).
- Sentry Performance is trace-focused — great for "why is this API slow", weaker for "what did 50% of mobile users on 4G see".
- Speed Insights is real-user, captures every Web Vital from real devices and real networks. The only signal Google ranks SEO on.
Together = full picture. Each is free with no card.