Performance Optimization

Measure before optimizing. Performance work without measurement is guessing — and guessing leads to premature optimization that adds complexity without improving what matters. Profile first, identify the actual bottleneck, fix it, measure again. Optimize only what measurements prove matters.

When to Use This Skill

Use this skill when:

• Performance requirements exist in the spec (load time budgets, response time SLAs, LCP/INP/CLS targets)
• Users or monitoring report slow behavior (high latency, sluggish interactions, jank)
• Core Web Vitals scores are below 'Good' thresholds
• You suspect a recent change introduced a performance regression
• Building features that handle large datasets or high traffic volumes
• Profiling or tracing reveals a bottleneck that needs addressing
• An N+1 query pattern is discovered in data-fetching code
• Bundle size analysis shows large, unnecessary dependencies

When NOT to use: Do not optimize before you have empirical evidence of a problem. Premature optimization is a known source of bugs, complexity, and wasted effort. If you're guessing at what's slow, measure first.