note: it was just an example. but in the end from a performance optimization standpoint it is a lot about what information you want to give to help the compiler along at doing its best job. with many compilers/languages that tends to be value semantics; however specifically in Fortran, which defaults to immutable reference semantics, reference types tend to be very straightforward to work together with the machine, avoid additional and keep functions inline-able. Overall from my experience this creates a more performant baseline when non-engineers work with it.