The author is saying that the main reason to use something like C++ instead of Python or even Java is for speed. He assumes that optimizing for speed is a probl

The author is saying that the main reason to use something like C++ instead of Python or even Java is for speed. He assumes that optimizing for speed is a problem that can fit neatly under the machine learning domain. If a machine can optimize performance better than humans, then it would not make sense to use C++, in the context of performance.