> As to other approaches attempted: I also tried enabling the kernel to use pre-compiled headers (with GCC), which didn't bring a performance improvement beyond

> As to other approaches attempted: I also tried enabling the kernel to use pre-compiled headers (with GCC), which didn't bring a performance improvement beyond a 1-2% for repeat builds. Plus during development most of the precompiled headers are cache-cold in any case and need to be generated by the compiler again and again.