[gpderetta]

> With C++ or rust, if you add dynamic dispatch, unless you are doing PGO and whole program optimization, you are pretty much sunk with 2 memory lookups on every function call. This is the case where javascript can end up beating C++/Rust.

GCC at least is capable of speculative devirtualization by using local heuristics, without PGO. And of course it is capable of devirtualizing in many cases when the knowledge actual type can be constant-propagated.

Also note that the vast majority of calls are not dynamic in C++ (as opposed to most dynamic languages), so devirtualization is significantly less impactful.

[cogman10]

Fair point, AFAIK C++ templates are pretty heavily used to avoid a dynamic dispatch. Couple that with the fact that polymorphic OO has fallen out of favor generally and I could see this mattering a lot less now-a-days.