#web-performance

Next.js 16 flipped the caching default: nothing is cached unless you write 'use cache'. That sounds like a footgun and turns out to be the fix. Here's the mental model that makes Partial Prerendering click, and the traps that hang your build for 50 seconds.

The server-client boundary is a clean idea. The runtime serialization errors it throws at 2am are not. Here's what breaks when React Server Components meet real traffic, plus the CVSS 10.0 flaw that hit the whole ecosystem in December 2025.

A CDN puts copies of your content on servers near your users so the bytes travel a short distance instead of crossing an ocean every request. The thing most people miss: the bottleneck usually isn't bandwidth, it's latency, and latency is bounded by the speed of light.