The class library is a beginner's step into programming with the Visual Basic and C# languages. Once you are confident in how to use the toolkit, I seriously suggest using the Interop library which is what I have used with my Asteroids game. (See sticky)
Yes, there is a slight bottle neck because of the wrapper, but lets be honest, using the advanced interop functionality of DarkGDK.NET, is alot easier to setup and use if you have had difficulties with Headers and Compiler errors when using C/C++. This was the whole point of developing DarkGDK.NET in the first place, to remove the complexities of C/C++ compiling complications.
It's not fast, and we all know this, but if you use the Interop library with good optimized VB/C# code, the differences are very close to using DarkGDK alone.
Paul.