CDN vs. Cache: Understanding Modern Speed Optimizations
Introduction
Both caching and Content Delivery Networks (CDNs) boost web performance, but they solve different problems. Knowing when to use each (and when to combine them) is key to fast, resilient experiences.
How they work
Cache stores copies of data closer to where its neededinside the browser, at the edge, or on your serversreducing compute and round-trips for repeat requests.
CDNs replicate site assets (images, scripts, video, downloads) across geographically distributed servers, shortening the physical distance between users and your content.
Use cases
- Cache: dynamic pages with partial caching, API/database responses, rendered HTML fragments, user-specific assets with safe TTLs.
- CDN: static files, large media, software downloads, and globally distributed audiences.
Comparison table
| Feature | Cache | CDN |
|---|---|---|
| Location | Local (browser), server, or edge | Globally distributed POPs |
| Main benefit | Faster repeat access & lower compute | Lower latency worldwide |
| Best for | Dynamic content & DB/API responses | Static files & large media |
| Failure isolation | Good for origin hotspots | Good for regional spikes/outages |
Conclusion
Cache and CDN are complementary: cache trims redundant work and tail latency near the app, while a CDN delivers static assets closer to users. Combining both usually yields the best speed, cost, and reliability.
Tip: Small, reversible changes compound into big winskeep rollbacks fast and easy.