(that may be where you got your 60MB/s number from)

It's not that. I think I messed up and the 0.1 seconds was tcc and msvc was 1 or 2 seconds. Nothing was 27 seconds. Try tcc, even though you are in a VM it should be very fast as a baseline for what's possible.

The point is that some people talk about single header files being slow are really saying "what if". C is incredibly fast to compile and the slow parts are the overhead from each compilation unit and the optimizers.

287 KB of source code added to a compilation unit is nothing in the modern era. Not only that, but you can just choose to put a lot of them in the same compilation unit and not touch it again.

Every time I've used single file header libraries it makes things simple and fast. I'm not going to change them so dumping them all into a single compilation unit is fine.