Performance
Skill plugin87/ux-ui-agent-skills/.claude/skills/performance
Turn Claude into a Senior Design Architect — DTCG design tokens, 42 components, WCAG 2.2 accessibility, any-framework code, 138 design systems, and runnable skills.
npx -y skills add plugin87/ux-ui-agent-skills --skill performanceAssembled from the repository path, not quoted from the project. Check it against their README if it does not work.
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What its author says it does
Copied from the file, not written here
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.
SKILL.md
1.6 KB, 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
- Read
workflows/performance.md(Core Web Vitals targets, loading strategy, layout-shift, animation perf, design-system runtime cost). - Diagnose against budgets: LCP ≤ 2.5s, INP ≤ 200ms, CLS ≤ 0.1. Measure on a mid-tier mobile profile (throttle slow 4G + 4× CPU).
- 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.
- Kill layout shift: size skeletons to final dimensions, reserve media space via
aspect-ratio(tokens/sizing.json), never inject content above existing. - Animation: only
transform/opacity,will-changesparingly, 100–300ms (tokens/motion.json), honorprefers-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.
Gives 0 of the 12 instructions most performance cost skills give
Counted across 803 of the 1,058 authors here whose files we hold, read 2026-08-06
- keep skill files under 500 linesin 82 of 803, across 17 files
- use imperative form in instructionsin 81 of 803, across 10 files
- draft assertions while test runs are in progressin 75 of 803, across 9 files
- create two to three realistic test promptsin 74 of 803, across 8 files
- write skill descriptions to be pushyin 72 of 803, across 7 files
- save test cases to evals jsonin 72 of 803, across 6 files
- ask questions about edge cases and input formatsin 71 of 803, across 6 files
- save timing data immediately when runs completein 70 of 803, across 5 files
- include all trigger conditions in the skill descriptionin 69 of 803, across 3 files
- launch all test runs in a single turnin 69 of 803, across 3 files
- capture intent before writing a skillin 67 of 803, across 1 file
- import directly instead of barrel filesin 52 of 803, across 15 files
Said here and by no other author read
- read the performance workflow
- diagnose against Core Web Vitals budgets
- measure on a mid-tier mobile profile
- render above-fold first
- lazy-load below-fold or behind-interaction content
- size skeletons to final dimensions
Grouped from the skills themselves: near-identical wordings counted once, and counted by distinct author, so one author publishing three of these counts once.