How to Use Performance Budgets in Web Projects

· Category: Web Performance

Short answer

A performance budget sets limits on metrics like page weight or load time. It prevents regressions by failing builds when limits are exceeded.

Steps

  1. Define budgets based on competitor analysis or business goals.
  2. Set limits for total JavaScript size, image weight, and specific metrics like LCP.
  3. Integrate budget checks into your build pipeline with Lighthouse CI.
  4. Monitor budgets in production with RUM tools.
  5. Review and tighten budgets quarterly as performance improves.

Tips

  • Start with a generous budget and tighten it iteratively.
  • Allocate separate budgets for mobile and desktop experiences.
  • Treat performance budgets like test coverage; they are team agreements.

Common issues

  • Budgets without enforcement are ignored.
  • Third-party scripts often push projects over budget unexpectedly.