Ah the configure scripts and large c++ codebases, the bane of fast compile times. Configure scripts "checking useless stuff" isn't parallelized so it takes ages, even on a modern beefy processor. Somebody should write ccache-like thing just for autoconfigure, so it can instantly feed answer to those checks once it has once run and cached the result, maybe this could even be part of ccache (I don't mean just the preprocessing part, but whole thing).