Web performance audit

Skill secondsky/claude-skills/plugins/web-performance-audit/skills/web-performance-audit

Production-ready skills for Claude Code CLI - Cloudflare, React, Tailwind v4, and AI integrations

Install

npx -y skills add secondsky/claude-skills --skill web-performance-audit

Assembled from the repository path, not quoted from the project. Check it against their README if it does not work.

What its author says it does

Copied from the file, not written here

Web performance audits with Core Web Vitals, bottleneck identification, optimization recommendations. Use for page load times, performance reviews, UX optimization, or encountering LCP, FID, CLS issues, resource blocking, render delays.

The file declares its own license as MIT. That is the author’s claim about this one file, and it is not the same thing as the license GitHub reports for the repository, which is listed with the other numbers below.

SKILL.md

2.5 KB, 616 tokens by cl100k_base, as published. Nobody here has run it

Web Performance Audit

Conduct comprehensive performance audits and implement optimizations.

Core Web Vitals Targets

Metric	Good	Needs Improvement	Poor
LCP (Largest Contentful Paint)	<2.5s	2.5-4s	>4s
FID (First Input Delay)	<100ms	100-300ms	>300ms
CLS (Cumulative Layout Shift)	<0.1	0.1-0.25	>0.25
INP (Interaction to Next Paint)	<200ms	200-500ms	>500ms

Performance Measurement

// Using web-vitals library
import { getCLS, getFID, getLCP, getTTFB } from 'web-vitals';

function sendToAnalytics({ name, value, id }) {
  console.log({ name, value, id });
}

getCLS(sendToAnalytics);
getFID(sendToAnalytics);
getLCP(sendToAnalytics);
getTTFB(sendToAnalytics);

Lighthouse Automation

const lighthouse = require('lighthouse');
const chromeLauncher = require('chrome-launcher');

async function runAudit(url) {
  const chrome = await chromeLauncher.launch({ chromeFlags: ['--headless'] });
  const result = await lighthouse(url, {
    port: chrome.port,
    onlyCategories: ['performance']
  });

  await chrome.kill();
  return result.lhr;
}

Optimization Strategies

Quick Wins (1-2 days)

Enable gzip/brotli compression
Minify CSS/JS
Defer non-critical scripts
Optimize images (WebP, lazy loading)

Medium Effort (1-2 weeks)

Implement code splitting
Add service worker caching
Preload critical resources
Eliminate render-blocking resources

Long-term (1-3 months)

Architecture improvements
CDN optimization
Database query optimization

Performance Budget

{
  "timings": [
    { "metric": "first-contentful-paint", "budget": 1500 },
    { "metric": "largest-contentful-paint", "budget": 2500 }
  ],
  "resourceSizes": [
    { "resourceType": "script", "budget": 150 },
    { "resourceType": "image", "budget": 300 }
  ]
}

Audit Checklist

Measure baseline Core Web Vitals
Run Lighthouse audit (mobile & desktop)
Analyze real user metrics (RUM)
Identify largest contentful element
Check for layout shifts
Review JavaScript bundle size
Test on slow 3G connection
Set performance budget
Configure monitoring alerts

Gives 0 of the 12 instructions most audit compliance skills give in 616 tokens

Counted across 936 of the 1,487 authors here whose files we hold, read 2026-08-06

group findings by severityin 44 of 936
Fetch latest guidelines before each reviewin 43 of 936, across 3 files
Check files against all fetched rulesin 42 of 936, across 2 files
Output findings in terse file:line formatin 41 of 936, across 3 files
Ask user which files to review if none specifiedin 41 of 936, across 3 files
Read specified files or prompt user for filesin 39 of 936, across 1 file
generate the audit reportin 39 of 936, across 36 files
assign a severity to every findingin 25 of 936
run automated accessibility scansin 23 of 936, across 13 files
map findings to WCAG criteriain 20 of 936, across 10 files
confirm audit scopein 19 of 936, across 9 files
check title tags and meta descriptions for uniquenessin 19 of 936, across 5 files

Grouped from the skills themselves: near-identical wordings counted once, and counted by distinct author, so one author publishing three of these counts once. Length counted with cl100k_base; the agent that loads this file may tokenize it differently.