OTOH, 99% of use cases don't care about performance and just want a portable implementation.
While it could be useful to have a "fast" variation that offers no guarantee at all, what you would end up with (because people are vain) is that too may people would use those instead "because perf", even though the actual usage is not performance critical, and have code that breaks whenever the compiler or platform changes.
While it could be useful to have a "fast" variation that offers no guarantee at all, what you would end up with (because people are vain) is that too may people would use those instead "because perf", even though the actual usage is not performance critical, and have code that breaks whenever the compiler or platform changes.