JavaScript · Performance · Tech Lead · Architecture
How would you build a performance culture for a JS frontend org (budgets, tooling, ownership)?
Short Interview Answer
Set Core Web Vital budgets, RUM + lab CI gates, clear owners per surface, and make performance a release criterion—not a one-off project.
Detailed Explanation
Define budgets (LCP/INP/CLS, JS KB gzipped per route). Instrument RUM (real users) and synthetic checks on critical journeys. Fail CI on bundle regressions and lab regressions beyond thresholds. Assign feature owners; require perf impact in RFCs for heavy UI. Provide playbooks for images, fonts, JS. Educate via reviews and dashboards. Balance business features with degradation strategies. Avoid vanity micro-benchmarks without user impact. Celebrate wins with metric deltas.
Interview Tip
Stress RUM + CI + ownership triad.
Common Mistake
One-time perf sprint with no ongoing budgets.