> Historically there was a big performance hit for using the fancy added abstractions of C++. Don't know if it's still that bad. But in the past it cost a factor of two or so, whenever I tried to get fancy.

I don't know how much back in the past it is, but pretty much every time in the last ten years I tried to beat a C++ abstraction, I almost never managed to substantially improve (and since gcc.godbolt.org exists it made it much easier to witness that most of the abstraction layers entirely disappear at -O2)

Historically, meaning "in the '90s". It has been quite a long time since the '90s. Many readers here weren't even born yet when C++ abstraction overhead was last a thing.