I work on a project that uses C++. Our runtime is implemented in C++, and our compiler produces C++. For us, performance is a top priority. I am quite frustrated by C++ sometimes, but I think it's the best tool for our job. I'm quite fond of pure C, but I also like having rich abstraction mechanisms like classes and templates, so I don't think it's appropriate for us. And no other language with broad support is as well-suited to writing high performance systems code while also allowing us to have rich abstraction mechanisms.

I am interested in D for this purpose - the most recent version looks quite well designed - but it's not as widely supported.