Performance is largely architectural for most types of software. The extreme difficulty of redesigning architecture after the software is feature complete (it a

Performance is largely architectural for most types of software. The extreme difficulty of redesigning architecture after the software is feature complete (it approximates a rewrite) makes it a requirement that any performance and efficiency considerations be designed into the system from day one. Optimizations you can add later are always severely constrained by the kinds of optimizations the architecture allows. In most software I see, the "performance later" designs tacitly remove most possibility of macro-optimization. Not all software needs to care about performance, but I also see a lot of large multi-server monstrosities that could easily be run simply and cleanly on a single server with capacity to spare if more thought had been put into performance and efficiency.