How to use
- Copy the installation command and review the source package before installing it in your own agent environment.
- Check the source document for required tools, credentials and supported hosts.
- Describe your input and desired deliverable; review the output against the source material.
npx skills add https://github.com/plugin87/ux-ui-agent-skills --skill performanceBefore you start
- Installation does not include a model subscription, API allowance or permission to access your files.
- Repository stars and installation counts describe activity, not an independent quality or security test.
Original skill document
Rendered from the source repository. Headings, examples, code, tables, links, and referenced images are preserved.
Skill: Performance
Step 0 — is the kit here? This skill reads files from the kit. Check once:ls ${CLAUDE_SKILL_DIR}/../../../tokens >/dev/null 2>&1 && echo KIT_OK || echo KIT_MISSINGOnKIT_MISSINGonly the skill folders were installed, which is whatnpx skills adddoes. Say so plainly, point the user atnpx ux-ui-agent-skills initor the plugin install, and stop. Do not guess the contents of a file you could not open.
Make the UI fast and stable. Treat performance as an accessibility concern — slow/janky UIs fail low-end devices first.
Steps
- Read
${CLAUDE_SKILL_DIR}/../../../workflows/performance.md(Core Web Vitals targets, loading strategy, layout-shift, animation perf, design-system runtime cost). - Diagnose against budgets: LCP ≤ 2.5s, INP ≤ 200ms, CLS ≤ 0.1. Measure on a mid-tier mobile profile (throttle slow 4G + 4× CPU).
- Loading: render above-fold first (SSR/Server Components), code-split by route + heavy widget, lazy-load below-fold/behind-interaction (Astro islands / Qwik), preload one critical font weight, modern responsive images.
- Kill layout shift: size skeletons to final dimensions, reserve media space via
aspect-ratio(${CLAUDE_SKILL_DIR}/../../../tokens/sizing.json), never inject content above existing. - Animation: only
transform/opacity,will-changesparingly, 100–300ms (${CLAUDE_SKILL_DIR}/../../../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.
