-O2 seems to be the most commonly used optimization level. That's what most of the distro software and the kernel etc uses. In the past except for maybe a handf

-O2 seems to be the most commonly used optimization level. That's what most of the distro software and the kernel etc uses. In the past except for maybe a handful things, O3 was an overkill. (O3/Ofast remind me of my Gentoo days! :)