Question: Are there any aspects to the C++ programming language where the code is known to be slower than the equivalent C language? Obviously this would be excluding the OO features like virtual functions and vtable features etc.

I am wondering whether, when you are programming in a latency-critical area (and you aren't worried about OO features) whether you could stick with basic C++ or would C be better?

Answer: 
Contrary to what many C programmers like to think, one can often write tighter and faster code in C++ all without having to sacrifice a great deal in design.

I can't think of anything in C++ that is slower than its counterpart in C. Virtual functions NOT excluded.
There is no code in C++ whose direct equivalent in C is faster- or, indeed, more maintainable.