you can get the same performance by using the restrict keyword in C.

basically, C allows pointer aliasing while fortran does not, which means C programs need to be able to handle cases when a value is accessed from multiple locations. fortran does not, so a lot of accesses can be optimized into immediates, or unrolled without guards.

restrict is a pinky-promise to the compiler that no overlapping takes place, e.g. that a value will only be accessed from one place. it's basically rust ownership semantics without enforcement.