I've searched pretty much everywhere but I can't find a single source that has benchmarks about the compilation times with the new C++20 features like "Modules", "Concepts" etc.
So yeah, I heard that some features will improve the compilation times but I haven't found any benchmarks that show this in practice. Anyone that has found something?
I don't think Concepts speeds up compilation, rather the opposite because it has to do more work.
Modules are supposed to speed up compilation. I haven't used them myself yet. I found this paper: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1441r1.pdf The conclusion seems to be that modules normally speed up compilation but the traditional non-modular code scaled better with increased number of CPU cores so if you have a large number of cores modules might even be slower.