unique_ptr is nearly overhead free compared to a bare pointer (except for argument passing... because of ABI concerns). shared_ptr is expensive and easy to bui

unique_ptr is nearly overhead free compared to a bare pointer (except for argument passing... because of ABI concerns). shared_ptr is expensive and easy to build leaks with, so a lot of code bases avoid it where possible. Though it's only expensive when you copy it, moving it is ~free.