Sure, C++ is heavy for compilation, there's simply more by the compiler to do, but code repository building under 5 seconds is at the very low end of tail so making the point about someone bearing with the 5 seconds longer build time is sort of moot.

I wrote a lot of plain C and a lot of C++ (cumulatively probably close to MLoC) and I can't remember any C code that would compile in such a short time unless it was a library code or some trivial example.