C would be the obvious answer. It might be old, but it’s still the one that most directly translates to the assembly language that your code is going to get compiled to. I know lots of super high performance games at Nintendo are written in C++, but there’s still a lot of overhead there. It really depends on your target device. If you want to run on multicore x86 beasts, you could just about get away with anything. But if you want to run in resource constrained devices (Atmel chips, small ARM chips, etc.) then C is your friend.
You are correct, in my opinion. There is only one choice. After all these years, C/C++ is still the king. My choice for Windows development is still Delphi. I have Visual Studio and SQL Server for my web stuff.