Right at the moment a Safari user visits a website, even if they’ve never been there before or entered any personal information, a malicious website can uncover their first name, last name, work place, city, state, and email address.

It is tempting to think of compiler optimizations as reducing the constant in your program’s big-O complexity, and nothing else. They aren’t supposed to be able to make your program asymptotically faster, or affect its output.