@Luna: Do you know the answer? Which is it?
I am with you, there is no evidence, ..., but there is no evidence of the opposite case.

I don't know if everyone is talking as if these languages are destined to be slow, the only thing I know is that C++ was born to be fast (zero-overhead)...

These other languages have some features (or lack of) in which they can not compete with C++. Some of them have impact on performance.

- Poor value semantics
- Poor generic programming support
- Abuse of runtime instrospection as default practice
- Limited expressiveness (compared obviously with C++), see... http://www.codeproject.com/Articles/5676/Spart-a-parser-generator-framework-100-C
- Portability (C#)

I think that the only current evidence, it is reality, see...

On the other hand,I wouldn't think to code a simple web application in C++, where the main requirement is time-to-market (for now).