[dataflow]

> I mean if there is any library you want to be as fast as possible, it's the standard library.

To a decent extent yeah, though I would emphasize the issue isn't quite being as fast as possible (although in some cases it is, but also see I/O streams...), but rather having near-absolute correctness, and achieving high performance as a secondary goal. You can usually find a faster third-party implementation of anything in the C++ standard library. The problem is third-party implementations always cut corners somewhere, whether it's strong exception-safety, proper trait/concept handling, thorough testing of rare edge cases, extensibility/customizability, or other stuff. Even the syntactic complexity rises as a result, let alone the complexity of the actual semantics. (Even minor stuff like using difference_type/size_type instead of ptrdiff_t/size_t makes things more verbose and harder to read in the standard library; third-party implementations would often opt for the latter.)