This statement of programmers using only C for performance used to be true before. The advantage of a programming language like C is it's fast in terms of execution times but OO languages such as C++ and Java score better in terms of product development time and maintenance. It's much easier to develop code and debug it using OO languages than C. Now-a-days, the computing power has increased manifold and is much cheaper than before. Hence the developement and debug time has become more important than execution time concerns. Moreover, with distributed architectures, it is difficult to say applications written using OO languages are running slower than the ones written in C. 

Some of the low-level items such as kernel, device drivers etc. are still written in C, as C allows easy manipulation of hardware. But most application level programs these days are written in OO languages.

There are many examples of big companies using OO languages for development. I heard Google develops most of the applications in Java and C++. Microsoft is known to use Visual C++.