> In the vast majority of situations [..] yes the profiler will point to a single, easy-to-fix smoking gun. [citation needed] This claim depends hugely on the

> In the vast majority of situations [..] yes the profiler will point to a single, easy-to-fix smoking gun. [citation needed] This claim depends hugely on the industry you're actually working in and the problem space. Things like UIs & games basically never have a single, easy-to-fix smoking gun. The entire app is more or less a hotspot - be it interactive performance, startup performance, RAM usage, or general responsiveness. And once you're gone down the route of "build it first, optimize it later" you're pretty much fucked when you get to the "optimize" step because now your performance mistakes are basically unfixable without a rewrite - every layer of your architecture has issues that you can't fix without drastic overhauls. It would have been much easier to do some up-front measurements, get some guidelines in place (even if they aren't perfect), and then build the app.