It looks like we only set -mtune on some of our platforms, and use a default value otherwise. We should see if setting more specific values nets us any performance benefit. If we set -mtune more consistently, we can use std::hardware_constructive_interference_size and std::hardware_destructive_interference_size and actually gain their benefits (when the compiler doesn't know which platform to optimize for, it makes poor guesses and generates warnings that advertise that).