The CDN Is Doing More Work Than Your Code Is

It's easy to spend a build's worth of effort trimming bundle size and optimizing images, and then serve the result from a single origin with no edge caching in front of it — at which point every one of those optimizations is competing with network latency that has nothing to do with the code.

Cache headers are the unglamorous lever that actually moves the needle here: a page that's genuinely static but served with a short or missing cache lifetime forces a round trip to origin on every visit, regardless of how small the page itself is.

None of this is exotic — it's mostly making sure the deployment platform's defaults are actually the defaults you want, not the ones that happened to ship. It's just rarely the first place teams look when a static site feels slower than it should.