Performance should be treated as a product constraint, not a late audit.
Budget fields
- LCP (lab): <= 2.0s
- CLS: <= 0.05
- JS on critical route: <= 170KB gzip
Guardrails
Every PR touching core routes gets Lighthouse checks and a budget review.
Performance · 6 min
Next.js performance budget playbook
Performance budgets as a binding team contract for stable App Router delivery.