Just to make sure I'm understanding this correctly: the performance issue you found actually amounts to include-order dependent behavior in GCC and glibc; clang doesn't really have anything to do with anything here except that you used its code formatter to sort your include statements.
If that's the case, the clickbait-y headline's bordering on useless, since the performance differences here have nothing to do with clang itself-- you'd see the same results if you had ordered your includes the same way by hand.
If that's the case, the clickbait-y headline's bordering on useless, since the performance differences here have nothing to do with clang itself-- you'd see the same results if you had ordered your includes the same way by hand.