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name: cdn description: "Use when auditing slow page loads, heavy assets, or rendering delays related to Use a content delivery network. Verify the actual bottleneck in DevTools, Lighthouse, or field data before recommending changes." metadata: category: performance priority: high difficulty: intermediate estimatedTime: "30" source: frontendchecklist.io url: https://frontendchecklist.io/rules/performance/cdn

Use a content delivery network

A CDN serves static assets from geographically distributed servers—users download from the nearest location, dramatically reducing latency and improving load times.

Quick Reference

• CDNs serve content from edge servers closest to users
• Reduces latency by 50-70% for global users
• Handles traffic spikes and provides DDoS protection
• Popular options: Cloudflare, Vercel, AWS CloudFront, Fastly

Check

Check if static assets are served from a CDN and if the CDN is properly configured.

Fix

Configure a CDN to serve static assets with proper caching headers and geographic distribution.

Explain

Explain how CDNs reduce latency by serving content from geographically distributed servers.

Code Review

Review the routes, assets, and loading behavior that affect Use a content delivery network. Flag exact files, requests, or rendering steps that add unnecessary network, CPU, or layout cost, and describe the measurement method used to confirm the issue.

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For full implementation details, code examples, and framework-specific guidance, see references/rule.md.

Rule page: https://frontendchecklist.io/rules/performance/cdn