Ok, I see, thanks. Why then using C#/.NET at all if you have to do without many (most?) of the conveniences of this technology, and even have to consider to implement parts in C++ for performance reason? Why not directly e.g. C++?
There are some conveniences that come with the technology and not every code path on the game engine is screaming for perfomance.
If you are on the path for the ultimate performance like some console titles, the C and C++ code on those engines will be very alien to most developers as well, yet you don't seem many discussing that.
Just on the subject, here is a talk I saw recently on the theme,
"Beyond the Remake of 'Shadow of the Colossus': A Technical Perspective"
https://www.youtube.com/watch?v=fcBZEZWGYek
However not every single game out there is trying to fit Shadow of the Colossus into a PS 2 or XBox 360.