С++ is not exactly a comfortable language. While recent changes may be great, and there are quite nice libraries, the language still does little to prevent you from shooting yourself in the foot (and sometimes downright provokes it).
If I were about high speed, I'd take Java (which regularly rivals, and sometimes surpasses, C++ in speed), or Rust, or maybe Go. Other worthy contenders would be Haskell, OCaml, D, maybe even Elixir (unless they are CPU-heavy), though with these hiring becomes much harder than with Python or Java (and probably even C++).
If I were about high speed, I'd take Java (which regularly rivals, and sometimes surpasses, C++ in speed), or Rust, or maybe Go. Other worthy contenders would be Haskell, OCaml, D, maybe even Elixir (unless they are CPU-heavy), though with these hiring becomes much harder than with Python or Java (and probably even C++).