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.
- Installs
- 493
- Last 24h
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- Trending rank
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- Security
- Not audited
Install
Works with every agent the skills CLI supports.
npx skills add https://github.com/plugin87/ux-ui-agent-skills --skill performance- 01
Install
Run the command in your project. The CLI asks which agents to install for.
- 02
Describe the task
Ask your agent for something this skill covers. It loads performance automatically when relevant.
- 03
Review the result
The agent follows the SKILL.md steps, scripts and references bundled with the skill.
SKILL.md
The instructions your agent reads when the skill is triggered.
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.
FAQ
What does the performance skill do?
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.
How do I install performance?
Run npx skills add https://github.com/plugin87/ux-ui-agent-skills --skill performance in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/performance/ (personal) or .claude/skills/performance/ (project).
Which AI agents can use performance?
Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.
Is performance safe to install?
No partner security audit is available yet. Skills can run commands and scripts, so read the SKILL.md and any bundled files before installing.
Who maintains performance?
It is published by plugin87 in plugin87/ux-ui-agent-skills. It has 493 recorded installs.
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