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Agent skill

Performance

by plugin87 in plugin87/ux-ui-agent-skills

Optimize UI performance against Core Web Vitals — LCP, INP, CLS — with loading/code-split strategy, layout-shift prevention, and animation performance rules.

MITAuto-check passedFrontend & Design

Install Performance

skills CLI
$ npx skills add plugin87/ux-ui-agent-skills --skill performance -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install plugin87/ux-ui-agent-skills performance --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/plugin87/ux-ui-agent-skills.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.claude/skills/performance .claude/skills/performance && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
performance
GitHub stars
1.5k
Token cost
~541 tokens
SKILL.md length
228 words
Files
1
Skills in repo
23
Repo updated
First seen
Licence
MIT

At a glance

Optimize UI performance against Core Web Vitals — LCP, INP, CLS — with loading/code-split strategy, layout-shift prevention, and animation performance rules.

  • Works in 5 steps: Read… → Diagnose against budgets: LCP ≤ 2.5s,… → Loading: render above-fold first… → …
  • The user wants to improve speed
  • SKILL.md covers Steps and Verification (definition of…
  • Calls npx

What it does

Performance is an agent skill from plugin87/ux-ui-agent-skills. 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.

Its SKILL.md is about 540 tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Frontend & Design, covering Web performance. The repository describes itself as: Turn Claude into a senior design architect: DTCG tokens, 52 components, WCAG 2.2 AA-AAA, 138 design systems, any-framework code, and 50 objective gates that fail the build… The licence is MIT.

When your agent uses it

  • The user wants to improve speed
  • Hit Web Vitals budgets
  • Make a UI feel fast on low-end devices

Example prompts

  • “/performance”

Requirements

  • Node.js

Workflow steps

5 steps, taken from the first numbered list in SKILL.md.

  1. Read ${CLAUDE_SKILL_DIR}/../../../workflows/performance.md (Core Web Vitals targets, loading strategy, layout-shift, animation perf…
  2. Diagnose against budgets: LCP ≤ 2.5s, INP ≤ 200ms, CLS ≤ 0.1. Measure on a mid-tier mobile profile (throttle slow 4G + 4× CPU).
  3. Loading: render above-fold first (SSR/Server Components), code-split by route + heavy widget, lazy-load below-fold/behind-interaction…
  4. Kill layout shift: size skeletons to final dimensions, reserve media space via aspect-ratio…
  5. Animation: only transform/opacity, will-change sparingly, 100–300ms (${CLAUDE_SKILL_DIR}/../../../tokens/motion.json), honor…

What it can do on your machine

Read from SKILL.md and the folder at commit 14f8d44. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    Shell commands in SKILL.md call:

    • npx

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md. Its commands use npx, which can reach the network depending on how they are called.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Performance loads about 541 tokens when it runs. Until then it costs about 76 tokens; SKILL.md has 228 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~76
When it runs · the whole SKILL.md, loaded when a task matches
~541

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from plugin87/ux-ui-agent-skills at commit 14f8d44, republished under its MIT licence (© plugin87). 228 words, ~541 tokens.

Download SKILL.mdSave it as .claude/skills/performance/SKILL.md (or your agent's skills folder).
name
performance
description
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: 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_MISSING On KIT_MISSING only the skill folders were installed, which is what npx skills add does. Say so plainly, point the user at npx ux-ui-agent-skills init or 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

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

© plugin87, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in .claude/skills/performance of plugin87/ux-ui-agent-skills.

Open the folder on GitHubat commit 14f8d44

Compare with similar skills

Performance next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Performance compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Performance this skillplugin87/ux-ui-agent-skills1.5k—~541Automated safety check: PassMIT
React Doctormakeplane/plane60k12 repos~657Automated safety check: PassAGPL-3.0
Fixing Motion Performanceibelick/ui-skills9.4k5 repos~1.4kAutomated safety check: PassMIT
GSAP Performance Tuninggreensock/gsap-skills16k4 repos~1kAutomated safety check: PassMIT
React Frontend Development Guidelinesdiet103/claude-code-infrastructure-showcase10k2 repos~2.9kAutomated safety check: PassMIT
Web Quality Auditaddyosmani/web-quality-skills2.9k—~2.6kAutomated safety check: PassMIT

Similar skills

  • React Doctor

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    Scans React code for lint, accessibility, bundle size and architecture issues, reports a health score and checks that changes do not lower it.

    60k GitHub starsUsed in 12 repos~657 tokens
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  • Fixing Motion Performance

    ibelick/ui-skills

    Audits and fixes web animation performance: layout thrashing, work that belongs on the compositor, scroll-linked motion and costly blur effects.

    9.4k GitHub starsUsed in 5 repos~1.4k tokens
    Frontend & DesignAuto-check passed

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    Guidelines for React 18 and TypeScript apps covering Suspense data fetching, lazy loading, feature folders, MUI v7 styling, TanStack Router and performance.

    10k GitHub starsUsed in 2 repos~2.9k tokens
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Categories

Questions about Performance

What does Performance do?

Optimize UI performance against Core Web Vitals — LCP, INP, CLS — with loading/code-split strategy, layout-shift prevention, and animation performance rules. Performance is an agent skill from plugin87/ux-ui-agent-skills. Optimize UI performance against Core Web Vitals — LCP, INP, CLS — with loading/code-split strategy, layout-shift prevention, and animation performance rules.

When should I use Performance?

Performance fits situations like: the user wants to improve speed; hit Web Vitals budgets; make a UI feel fast on low-end devices.

How do I install Performance in Claude Code?

Run `npx skills add plugin87/ux-ui-agent-skills --skill performance -a claude-code`. Or copy the skill folder (.claude/skills/performance in plugin87/ux-ui-agent-skills) into .claude/skills/performance in your project. Claude Code loads it when a task matches its description.

How do I install Performance in Codex?

Run `npx skills add plugin87/ux-ui-agent-skills --skill performance -a codex`. Or copy the skill folder (.claude/skills/performance in plugin87/ux-ui-agent-skills) into .agents/skills/performance in your project. Codex loads it when a task matches its description.

Can I use Performance in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add plugin87/ux-ui-agent-skills --skill performance -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/performance, .gemini/skills/performance, .github/skills/performance and .opencode/skills/performance in your project.

What does Performance need to run?

Going by SKILL.md and its folder, Performance needs the command-line tools its instructions call (npx). Our summary lists: Node.js.

Does Performance access the network?

SKILL.md contains no URLs. Its commands use npx, which can reach the network depending on how they are called. This is read from the text; nothing was executed.

Is Performance safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Performance use?

Performance is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Performance use?

About 541 tokens (SKILL.md is roughly 2.2k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Performance?

Skills that share tags, products or a category with Performance: React Doctor (makeplane/plane, 60k stars), Fixing Motion Performance (ibelick/ui-skills, 9.4k stars), GSAP Performance Tuning (greensock/gsap-skills, 16k stars) and React Frontend Development Guidelines (diet103/claude-code-infrastructure-showcase, 10k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Performance?

plugin87 (a GitHub user) maintains it in plugin87/ux-ui-agent-skills, which has 1,543 GitHub stars. The repository holds 23 skills in this directory. The repository was last updated on October 7, 2026.

Source: plugin87/ux-ui-agent-skills on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.