web-performance-audit（网络性能审计）

Web Performance Audit

Table of Contents

• Overview
• When to Use
• Quick Start
• Reference Guides
• Best Practices

Overview

Web performance audits measure load times, identify bottlenecks, and guide optimization efforts to create faster, better user experiences.

When to Use

• Regular performance monitoring
• After major changes
• User complaints about slowness
• SEO optimization
• Mobile optimization
• Performance baseline setting

Quick Start

Minimal working example:

Core Web Vitals (Google):

Largest Contentful Paint (LCP):
  Measure: Time to load largest visible element
  Good: <2.5 seconds
  Poor: >4 seconds
  Impacts: User perception of speed

First Input Delay (FID):
  Measure: Time from user input to response
  Good: <100 milliseconds
  Poor: >300 milliseconds
  Impacts: Responsiveness

Cumulative Layout Shift (CLS):
  Measure: Visual stability (unexpected layout shifts)
  Good: <0.1
  Poor: >0.25
  Impacts: User frustration

---

Additional Metrics:

First Contentful Paint (FCP):
// ... (see reference guides for full implementation)

Reference Guides

Detailed implementations in the references/ directory:

Best Practices

✅ DO

• Measure regularly (not just once)
• Use field data (real users) + lab data
• Focus on Core Web Vitals
• Set realistic targets
• Prioritize by impact
• Monitor continuously
• Setup performance budgets
• Test on slow networks
• Include mobile in testing
• Document improvements

❌ DON'T

• Ignore field data
• Focus on one metric only
• Set impossible targets
• Optimize without measurement
• Forget about images
• Ignore JavaScript costs
• Skip mobile performance
• Over-optimize prematurely
• Forget about monitoring
• Expect improvements without effort