Fast builds for C++ require unending diligence from day 1. Part of my team’s CI is a build time check. Our code base runs to 10mm lines of code; clean uncached

Fast builds for C++ require unending diligence from day 1. Part of my team’s CI is a build time check. Our code base runs to 10mm lines of code; clean uncached builds are 3m; cached builds are 30s; incremental builds are in the 100s of ms range. The entire system is a single, short Makefile combined with ccache. There’s no fine-grain dependency tracking, so our builds never go wrong.