C was designed for general purpose computing like operating systems, while fortran was specifically for numerical simulations (for science) and not much else.

C was designed for general purpose computing like operating systems, while fortran was specifically for numerical simulations (for science) and not much else. Due to this legacy, Fortran has better support for arrays, and multidimensional arrays. Also, famously, in Fortran, pointers to data passed to functions are assumed to point to non-overlapping data regions, which allows better optimization of code. C doesn't generally assume this. Apart from that, my understanding is that the "Og" status accounts for a lot of the rest. Fortran compilers are very well optimized.