If C++ is just as fast as C except when it's not, then it's not as fast as C. More importantly, it's not easy to tell when you're going to hit performance issu

If C++ is just as fast as C except when it's not, then it's not as fast as C. More importantly, it's not easy to tell when you're going to hit performance issues with C++. You need an obscene amount of knowledge of both the language as well as hardware to get a sense of what to use to match C performance.