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8.7Metrics to Track Over Time
Beyond pass/fail, track these trends in your performance dashboard:
| Metric | Tracking Purpose | Alert Threshold |
|---|---|---|
| LCP trend (30-day) | Gradual degradation detection | 10% increase from baseline |
| Bundle size trend | JavaScript bloat detection | 5% increase per quarter |
| Lighthouse score trend | Overall quality trajectory | Score drops below 85 |
| Budget failure rate | Process health | > 20% of PRs fail on performance |
| Time to fix budget failures | Team responsiveness | > 3 days to resolve |
Performance budgets are not a one-time setup. They require ongoing maintenance, calibration, and team commitment to be effective. The payoff is a product that stays fast as it grows.