John, yes, you can use unmanaged code from a managed program. Java has the "Java Native Interface" and C# has "P/Invoke" - "platform invocation".
Regarding the performance: Anybody here writing Doom 4 or Quake 5 that you really need that kind of speed? Just kidding. ;-)
Regarding the performance: Anybody here writing Doom 4 or Quake 5 that you really need that kind of speed? Just kidding. ;-)