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Performance

Skill plugin87/ux-ui-agent-skills/.claude/skills/performance

Optimize UI performance against Core Web Vitals — LCP, INP, CLS — with loading/code-split strategy, layout-shift prevention, and animation performance rules. Use when the user wants to improve speed, fix jank or layout shift, hit Web Vitals budgets, or make a UI feel fast on low-end devices.From its SKILL.md

Install
npx -y skills add plugin87/ux-ui-agent-skills --skill performance

Assembled from the repository path, not quoted from the project. Check it against their README if it does not work.

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SKILL.md

1.6 KB, 342 tokens by cl100k_base, as published. Nobody here has run it

Skill: Performance

Make the UI fast and stable. Treat performance as an accessibility concern — slow/janky UIs fail low-end devices first.

Steps

  1. Read workflows/performance.md (Core Web Vitals targets, loading strategy, layout-shift, animation perf, design-system runtime cost).
  2. Diagnose against budgets: LCP ≤ 2.5s, INP ≤ 200ms, CLS ≤ 0.1. Measure on a mid-tier mobile profile (throttle slow 4G + 4× CPU).
  3. Loading: render above-fold first (SSR/Server Components), code-split by route + heavy widget, lazy-load below-fold/behind-interaction (Astro islands / Qwik), preload one critical font weight, modern responsive images.
  4. Kill layout shift: size skeletons to final dimensions, reserve media space via aspect-ratio (tokens/sizing.json), never inject content above existing.
  5. Animation: only transform/opacity, will-change sparingly, 100–300ms (tokens/motion.json), honor prefers-reduced-motion. Prefer CSS state styling over JS for low INP; tree-shake/per-component imports.

Verification (definition of done)

  • Lighthouse / field data meets LCP ≤ 2.5s, INP ≤ 200ms, CLS ≤ 0.1 on mid-tier mobile.
  • First interaction stays responsive under slow-4G + 4× CPU throttle.
  • Skeletons + media reserve space (zero CLS on load); no non-compositor animation in loops.

What ships with it

Read from the repository

Just SKILL.md. No reference files, no scripts.

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