https://gcc.gnu.org/bugzilla/show_bug.cgi?id=50160
--- Comment #47 from Jonathan Wakely <redi at gcc dot gnu.org> --- And for: std::vector<bool> v1(265); std::vector<bool> v2(265); v2.back() = true; it's nearly 20 times faster because this one only needs to do one bitwise comparison, not 60 of them. The time is dominated by the number of bitwise comparisons, so reducing that from O(N) to O(N % 64) makes a big difference.
