Performance

This one walks you through hitting Core Web Vitals targets (LCP under 2.5s, INP under 200ms, CLS under 0.1) on throttled mobile devices. It pushes server rendering or islands architecture for above-the-fold content, code splitting by route, and lazy loading everything else. The layout shift rules are practical: reserve space with aspect-ratio, size skeletons to match final content, never inject above existing elements. Animation discipline is strict, compositor-only properties with reduced motion support. The verification step actually throttles to slow 4G and 4× CPU, which will catch problems your MacBook won't. Treat this as accessibility work, because jank hits low-end devices hardest and performance budgets are really user-exclusion budgets.

skills.sh installs: 528
GitHub stars: 3.1K
last updated: Jun 11, 2026

View on GitHub

Install

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

Installs into .claude/skills of the current project.

Files

Skill: Performance

Requirements

This skill needs the full UX/UI Agent Skills kit: the gates, the references and the design-system library. Install it with npx ux-ui-agent-skills@3.1.0 init or as the Claude Code plugin. npx skills@1.7.6 add copies the skill folder and nothing else. Installed that way, this skill runs in guidance-only mode: no gate runs, so it gives no verdict.

Step 0: is the kit here? Check once: ls ${CLAUDE_SKILL_DIR}/../../../tokens >/dev/null 2>&1 && echo KIT_OK || echo KIT_MISSING On KIT_MISSING, open your reply with: "Guidance-only mode: the UX/UI Agent Skills kit is not installed here, so no gate ran and nothing below is measured." Then work from this file and general practice, under three rules. Do not guess or cite the contents of a kit file you could not open. State no measured number (no contrast ratio, no N/N, no "passes WCAG"): write "not verified" where one would go. End with a line Skipped (kit not installed): that names every gate script this file tells you to run, then the install command above.

SKILL.md on GitHub