Even now performance-critical code is assembly. Just take a look at your libc's memcpy implementation, for example. Most likely there's a default C implementation that is reasonably fast and a bunch of assembly versions for individual architectures.
The problem I have with this statement is that it implies other code, like the kernel, a ray-tracer, video editor, number crunching etc, stuff usually done in C/C++, are not "performance critical".
Let's call what you describe "extremely performance critical" if you wish.
With that said, MOST performance critical code is written in C/C++.
Code that's not that much performance critical is written in whatever.
