7.8Common Pitfalls

Flaky results from CI environments. CI runners have variable performance. Use numberOfRuns: 3 (or 5) and assert on the median, not a single run.

Budgets too tight. Start with achievable budgets and tighten them over time. A budget that fails on every PR gets disabled, defeating the purpose.

Ignoring mobile. Default Lighthouse settings simulate mobile. Do not change throttling to fast desktop to make numbers look good. Mobile is where most users are.

Not testing authenticated pages. Lighthouse CI supports puppeteerScript for login flows. Do not skip your most important pages just because they require authentication.

Budget drift. Review and update budgets quarterly. What was acceptable last year may not meet current user expectations or competitive standards.