I want two types of results: when developing, I want fast turnaround and most of the time don’t care about runtime performance; when deploying, I don’t care much about how long it takes to compile, but I want runtime performance to be optimised.
Even if it's a simple idea, IIRC Fabien Bellard suggested to use very simple compilers such as tcc for prototyping and gcc for final built. A few years ago there was also an intermediate step using clang for error messages (and also portability).