.net components in unmanaged code - performance?

I need to write some dll that will be loaded into some existing system via COM. How much performance do I lose if I开发者_Python百科 write using c#.net instead of plain c++?

In general, none.

Things to watch out for:

• Creating lots of strings by performing lots of string concats; but that in itself won't necessarily be a problem
• Excessive Boxing/Unboxing

Performance (C# and Visual Basic)