Performance Budget Lab
Use this skill to keep visually rich sites fast.
Own the budget and acceptance policy. Route measured runtime diagnosis, implementation fixes, and React/Next performance work to $performance-audit-websites.
Budget Areas
- JavaScript bundle size
- route-level code splitting
- image dimensions, formats, and lazy loading
- video poster, preload, autoplay, and reduced-data behavior
- font loading and fallback metrics
- animation cost and scroll handlers
- layout shift sources
- server rendering/static rendering choices
- caching and CDN behavior
Workflow
- Identify stack and deployment target.
- Inspect package dependencies and route structure.
- Define route, hardware/device, network/cache state and measurement method.
- Run Lighthouse or browser performance checks when feasible.
- Check Core Web Vitals (LCP, CLS, INP) and supporting diagnostics such as TTFB; choose metrics that measure the budgeted user experience.
- Set media/JavaScript/font budgets from the intended experience and baseline evidence.
- Prefer CSS and Motion for small interactions; reserve GSAP/R3F/video for clear value.
- Report tradeoffs honestly when visual richness costs performance.
Use Lighthouse or browser checks here to validate a budget decision, not to take ownership of deep runtime diagnosis. When the work shifts from setting thresholds to locating and repairing the bottleneck, hand off to $performance-audit-websites.
Output
Give:
- current risks
- recommended budgets
- measurement conditions and reconsideration rules
- commands run
- remaining uncertainty
Scope and evidence
Output a budget contract: route/device class, hardware, network/cache state, metric, threshold, test method and reconsideration condition. Route measured diagnosis/optimization to $performance-audit-websites; a budget-only request does not implement repairs.
