Amazon CloudFront: 6 Habits That Make Your Content Fast (and Cheap)
Six practical CloudFront habits — cache tuning, compression, origin shielding, smart invalidation, price-class control, and real-user monitoring — that cut latency and the CDN bill.
Your users won't wait for slow pages, and you shouldn't pay for bytes nobody re-reads from origin. CloudFront is AWS's CDN — a network of edge locations that cache your content close to users. Used well, it's the cheapest latency cut you'll ever buy. These six habits got me there.
1. Tune your TTLs, don't leave the defaults
CloudFront's default cache TTL is 24 hours with a zero minimum, which means one accidental Cache-Control header from your origin can pin stale content — or worse, "Cache-Control: no-cache" on everything makes CloudFront a very expensive proxy. Set explicit TTLs per behavior: images and fonts get long TTLs (a year, with versioned filenames), HTML gets short ones. Explicit beats accidental every time.
CloudFront's default cache TTL is 24 hours with a zero minimum, which means one accidental Cache-Control header from your origin can pin stale content — or worse, "Cache-Control: no-cache" on everything makes CloudFront a very expensive proxy. Set explicit TTLs per behavior: images and fonts get long TTLs (a year, with versioned filenames), HTML gets short ones. Explicit beats accidental every time.
2. Turn on compression and Brotli
Compression is a checkbox in the cache behavior settings and it's free bandwidth. Gzip plus Brotli cuts text payloads — HTML, CSS, JS, JSON — by 70-85%. I once watched a landing page drop from 1.4 MB to 260 KB with this single toggle. Origin Shield and fancy architectures mean nothing if you're shipping uncompressed text.
Compression is a checkbox in the cache behavior settings and it's free bandwidth. Gzip plus Brotli cuts text payloads — HTML, CSS, JS, JSON — by 70-85%. I once watched a landing page drop from 1.4 MB to 260 KB with this single toggle. Origin Shield and fancy architectures mean nothing if you're shipping uncompressed text.
3. Use Origin Shield before you reach for more origins
Every miss costs an origin fetch. Origin Shield adds a single regional caching layer in front of your origin so misses from many edge locations collapse into one origin request instead of dozens. If your origin is an ALB or S3 in one region and your users are global, Shield pays for itself in reduced origin load and fewer 5xx errors during traffic spikes.
Every miss costs an origin fetch. Origin Shield adds a single regional caching layer in front of your origin so misses from many edge locations collapse into one origin request instead of dozens. If your origin is an ALB or S3 in one region and your users are global, Shield pays for itself in reduced origin load and fewer 5xx errors during traffic spikes.
4. Invalidate like it costs money — because it does
The first 1,000 invalidation paths per month are free; after that you pay per path. Wildcard invalidations (/*) are convenient and expensive. Instead, version your static assets (app.abc123.js) so you never invalidate them at all, and invalidate only the HTML paths that actually change. A deployment pipeline that renames assets beats a pipeline that nukes the cache.
The first 1,000 invalidation paths per month are free; after that you pay per path. Wildcard invalidations (/*) are convenient and expensive. Instead, version your static assets (app.abc123.js) so you never invalidate them at all, and invalidate only the HTML paths that actually change. A deployment pipeline that renames assets beats a pipeline that nukes the cache.
5. Pick a price class that matches your users
CloudFront price classes let you limit which edge locations serve your content. If 95% of your users are in two regions, Price Class 100 (North America + Europe) can cut delivery costs noticeably versus serving every edge worldwide. Check your CloudFront access logs or the usage reports first — don't guess your traffic geography.
CloudFront price classes let you limit which edge locations serve your content. If 95% of your users are in two regions, Price Class 100 (North America + Europe) can cut delivery costs noticeably versus serving every edge worldwide. Check your CloudFront access logs or the usage reports first — don't guess your traffic geography.
6. Watch real-user latency, not just hit ratios
A 95% cache hit ratio sounds great until you realize the 5% misses are your checkout page. Enable CloudFront real-time logs or standard logs into S3 and actually read them: look at time-taken percentiles by path, origin latency, and error rates. Pair that with CloudWatch alarms on 5xx origin errors so you hear about origin problems before your users do.
A 95% cache hit ratio sounds great until you realize the 5% misses are your checkout page. Enable CloudFront real-time logs or standard logs into S3 and actually read them: look at time-taken percentiles by path, origin latency, and error rates. Pair that with CloudWatch alarms on 5xx origin errors so you hear about origin problems before your users do.
Key takeaways
- Explicit TTLs per behavior beat default caching — version static assets and stop invalidating them.
- Compression is free bandwidth: enable Gzip + Brotli on day one.
- Origin Shield collapses duplicate origin fetches for global audiences.
- Version filenames instead of wildcard-invalidating; pick a price class that matches real traffic; monitor path-level latency, not vanity hit ratios.
- Explicit TTLs per behavior beat default caching — version static assets and stop invalidating them.
- Compression is free bandwidth: enable Gzip + Brotli on day one.
- Origin Shield collapses duplicate origin fetches for global audiences.
- Version filenames instead of wildcard-invalidating; pick a price class that matches real traffic; monitor path-level latency, not vanity hit ratios.
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