The story
Ana runs small-group tours. Her site sells the way travel always has — with photographs of somewhere the reader would rather be, and itineraries detailed enough to picture the week.
Both of those are weight. A tour page carried thirty large images and a map embed, and her hosting sat in one country while her customers were spread across thirty. Before anything was cached, a visitor on another continent was paying for the distance twice: once for the round trip, and again for a server that rebuilt the page on arrival.
Cached as static HTML and pushed out through a CDN, the distance stops compounding. The images are converted and lazy-loaded, the booking flow is excluded so deposits always go through, and an itinerary that used to take seven seconds in Sydney now takes under one.