Yup, which is why a project that is serious about compilation time splits off type-independent parts into .cpp files that can be compiled separately, improving

Yup, which is why a project that is serious about compilation time splits off type-independent parts into .cpp files that can be compiled separately, improving the speed of compilation for users of that template. I consider being a header-only "library" a code smell. It's purely for convenience, at the cost of compilation speed.