Because Fortran was purpose-built for manipulating array-based data while C++ is a general-purpose programming language. That means Fortran is optimized for thi

Because Fortran was purpose-built for manipulating array-based data while C++ is a general-purpose programming language. That means Fortran is optimized for this problem domain starting at the _grammar of the language_ while C++ can provide at best access to a locally optimized set of libraries. Those libraries might be quite good, but the comparative experience is still like trying to drive a Phillips-head screw using a flat-head screwdriver.