A heavy, dynamic WordPress site can still load like a static one. Here is the four-layer cache and the one small purge manager that keeps it fast without ever serving a stale page.
How I run a fast, local-feeling site in many regions worldwide from a single small server, using an edge CDN, careful cache rules, and a repeatable deploy so adding a region is config not a rebuild.
A database that crashes under load is almost never a hardware problem, it is a memory math problem, and here is how I found the cause and fixed it on a real site without buying a bigger server.