Make the language easy to use without any mental burden? But you do realize programming is not easy, especially when you're aiming for high performance. How can you make a language easy to use "without any mental burden"? Programming is hard, programming well and with performance in mind is even more so. Some things you just can't magically make easy.

You can program with "performance in mind" in C and the big difference will be that the problem itself will be the obstruction, not the language.

In C++, you fight with the language first and then face the problem.

I actually feel the exact opposite when I program in C. C is so bare that most of my time is spent building the correct constructs I need to solve my problem. C++ on the other hand has a decent set of high level features that makes it easier for me to focus on the problem.

You can write a C++ program to solve a problem that looks almost exactly like the C program you would write. But C++ brings a couple of nice features, like resource management with constructors/destructors and type-safe data structures that you just can't have in C.

How can that be true, if C++ is (almost) a superset of C? Surely you can do anything in C++ identically to C, in the worst case scenario.

What fight are you having with C++?