performance-optimization

Diagnose and fix web performance issues including Core Web Vitals (LCP, INP, CLS), bundle size, asset optimization, render performance, and runtime efficiency. Use this skill whenever the user wants to improve page speed, fix Core Web Vitals, optimize assets, reduce bundle size, debug slow renders, or systematically improve a site's performance. Triggers on performance, page speed, Core Web Vitals, LCP, INP, CLS, FID, TTFB, bundle size, code splitting, image optimization, lazy loading, render blocking, slow page, performance audit, Lighthouse score. Also triggers when traffic or conversion is dropping due to perceived slowness.

Quality

85%

Does it follow best practices?

Run evals on this skill

Adds up to 20 points to the overall score

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Securityby

Low

Low-risk findings worth noting

Quality

Content

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Reviews the quality of instructions and guidance provided to agents. Good implementation is clear, handles edge cases, and produces reliable results.

The body is a well-structured, actionable reference with excellent progressive disclosure and a clear workflow. Its main weakness is conciseness: it re-explains Core Web Vitals basics and adds commentary Claude already knows, which could be trimmed without losing value.

Suggestions

Trim restatements of well-known concepts (CWV definitions, "Bad TTFB makes everything else worse", the 60-80% page weight stat) — assume Claude's knowledge and keep only the targets and fixes.

Make the Workflow's validation explicit and gating (e.g., "Re-run Lighthouse; do not proceed to the next fix until the targeted metric improves") rather than implied by step 6.

Collapse the per-metric "What it measures" lines into the section headers; the targets and cause/fix lists already convey the necessary information.

Dimension	Reasoning	Score
Conciseness	The body restates well-known concepts Claude already knows (standard CWV definitions and thresholds, "Bad TTFB makes everything else worse", "Images are typically 60 to 80 percent of page weight") — mostly efficient but padded with unnecessary explanation that could be tightened.	3 / 5
Actionability	Concrete thresholds (2.5s LCP, 170KB compressed JS, 1500 DOM elements) and specific fixes (scheduler.yield(), font-display: swap, tree-shake imports) give mostly executable guidance with only minor gaps, appropriate for an instruction-oriented skill.	4 / 5
Workflow Clarity	The 7-step Workflow is a clear sequence with a re-measure feedback loop (step 6), but validation checkpoints are implied rather than explicit gating steps, leaving minor validation gaps.	4 / 5
Progressive Disclosure	SKILL.md is a clear overview with a "Reference files" section linking three real, well-signaled one-level-deep references (audit-template.md, optimization-checklist.md, optimization-playbook.md), all confirmed present and described.	5 / 5
	Total	16 / 20 Passed

Description

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Based on the skill's description, can an agent find and select it at the right time? Clear, specific descriptions lead to better discovery.

The description is exemplary: it states concrete capabilities, an explicit "Use this skill whenever" trigger clause, comprehensive natural trigger keywords with synonyms, and a clearly distinct niche. It hits the top anchor on every dimension.

Dimension	Reasoning	Score
Specificity	"Diagnose and fix web performance issues including Core Web Vitals (LCP, INP, CLS), bundle size, asset optimization, render performance, and runtime efficiency" lists multiple concrete actions across a comprehensive set of capability areas.	5 / 5
Completeness	It clearly answers "what" (diagnose and fix web performance issues...) and explicitly answers "when" via "Use this skill whenever the user wants to improve page speed..." with concrete trigger phrases.	5 / 5
Trigger Term Quality	An extensive trigger list covers natural terms and synonyms ("performance, page speed, Core Web Vitals, LCP, INP, CLS, FID, TTFB, bundle size, code splitting, image optimization, lazy loading, render blocking, slow page, performance audit, Lighthouse score") that users would naturally say.	5 / 5
Distinctiveness Conflict Risk	The web-performance / Core Web Vitals niche is clearly distinct with specific triggers, and the body further separates it from qa-testing and seo-technical, minimizing conflict risk.	5 / 5
	Total	20 / 20 Passed

Validation

93%

Warnings & errors only

Checks the skill against the spec for correct structure and formatting. All validation checks must pass before discovery and implementation can be scored.

Validation — 15 / 16 Passed

Validation for skill structure

Criteria	Description	Result
frontmatter_unknown_keys	Unknown frontmatter key(s) found; consider removing or moving to metadata	Warning

	Total	15 / 16 Passed

Repository: rampstackco/claude-skills
Path: skills/performance-optimization/SKILL.md
Commit: 0479242

Reviewed: 14 days ago

Table of Contents

Discovery Implementation Validation

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