# Lighthouse scoring and audits — Web Performance Optimization

Source: https://www.geekswithgeeks.com/en/web-performance/web-perf-17

> Understand Lighthouse scoring methodology and use audit results to prioritize optimizations.

## Performance score calculation

Lighthouse scores weight metrics: FCP (10%), LCP (25%), Speed Index (15%), CLS (15%), TTI (10%), TBT (15%), others (10%). Improving LCP and CLS has highest impact. Score >= 90 is excellent, 50-90 good, <50 poor.

## Audit opportunities and diagnostics

Lighthouse lists specific issues: unoptimized images, unused JavaScript, slow server response, missing cache headers. Prioritize high-impact suggestions. Diagnostic metrics show underlying bottlenecks like unused CSS or render-blocking resources.

## Interpreting Lighthouse results

Focus on opportunities section, not just score. Test multiple times—results vary. Throttling affects measurements. Compare baseline vs. improved. Set incremental goals (e.g., 50 → 70 → 90).

Quick check

**Quiz:** What is the weight of LCP in Lighthouse scoring?

- [ ] 25%
- [ ] 15%
- [ ] 10%