nevertheless your argument doesnt hold in its formulation, c++ has more overhead at running time that C, an overhead which reduce its speed. if you write the 20% of code which use 80% of the time in C, and the 80% of your code which use 20% of the time in c++, your code *IS* slower, simply in a negigeable way.
I would be very interested in an example depicting what you mean (e.g. what kind of overhead etc.). It seems i can't follow your argumentation.
greetings, Thomas