You're shifting your claim.
No one I know who does high performance code (such as numerics, real time computer vision, that sort of thing) uses anything but C++, especially for new projects. There is nothing out there that combines the speed and expressivity of C++, and when you know performance is going to be a factor at some point, C++ is the only choice.
Check out something like Eigen or TooN (a somewhat more obscure library which is used in the vision world for things like PTAM). They are very far from C++. The code written down in an editor reads more like maths. There's no explict loops, no explicit memory allocation. They're both high performance libraries used in challenging applications (seriously download and run PTAM, it's amazing).
PTAM is decent C++ code with probably pretty decent performance, but it isn't "high performance numerical code" or even high performance embedded code; it contains none of the performance tuning that such code usually should have.
I think it is dishonest on your part to recommend Eigen, when you know (or ought to know) that it actually isn't high performance and is deeply mired in C++ idiosyncracies. Likewise, I think it is dishonest of you to portray C++ as the only high performance computing language in town, when you know full well that many people are using other languages, and you are simply not even familiar with those other languages.
I do use C++ a lot in my work and I recommend it to other people. But unlike you, I don't feel any need to lie about what it is and isn't. There are many alternatives to C++, and I think people should keep an open mind about what they use.