How do I reduce page load time with a CDN?

A CDN can reduce page load time by serving your static assets from servers closer to your users and by offloading traffic from your origin server.

What to put on a CDN

Typically:

• Images
• CSS
• JavaScript
• Fonts
• Video/audio files
• Other static files (PDFs, downloads)

How it helps

• Lower latency: Users download files from an edge server near them.
• Less origin load: Your main server handles fewer requests.
• Better caching: Repeated requests can be served instantly from cache.
• Improved global performance: Especially helpful for international users.

How to use a CDN effectively

1. Move static assets to the CDN

   • Change asset URLs to the CDN domain.
   • Example:
     https://cdn.example.com/images/logo.png

2. Set proper cache headers

   • Use long cache times for versioned files:
     • Cache-Control: public, max-age=31536000, immutable
   • For files that change often, use shorter cache times or cache revalidation.

3. Version your assets

   • Use file names or query strings like:
     • app.4f3c2.js
     • styles.v12.css
   • This lets you cache aggressively without serving stale content.

4. Enable compression

   • Use Brotli or gzip for text assets like HTML, CSS, JS.

5. Optimize images

   • Serve modern formats like WebP or AVIF when possible.
   • Resize images to the size actually displayed.

6. Use HTTP/2 or HTTP/3

   • Many CDNs support these by default and they improve delivery performance.

7. Avoid putting dynamic HTML on a CDN unless configured for it

   • CDNs are best for static or semi-static content.
   • For dynamic pages, use edge caching carefully if needed.

Common mistakes

• Caching everything with no invalidation plan
• Forgetting to update asset URLs
• Serving uncompressed assets
• Putting large unoptimized images on the CDN without resizing
• Not measuring before and after

How to measure improvement

Track:

• Time to First Byte (TTFB)
• Largest Contentful Paint (LCP)
• Total page load time
• Cache hit ratio
• Origin request volume

If you want, I can also show you:

• a step-by-step CDN setup
• how to do it for WordPress / React / Next.js
• or how to configure cache headers correctly.