Well if vector<SomeType> is used in many cpp files it is compiled separately for each and every one of them and then the linker throws away these gigantic amoun

Well if vector<SomeType> is used in many cpp files it is compiled separately for each and every one of them and then the linker throws away these gigantic amounts of code duplication between the various object files. Also vector<shared_ptr<T>> really only needs to be compiled once for all variations of T. I don't think much or even anything is to be gained by having copies of this code in the executable for every T.