Okay, now do it by percent of processor (CPU/GPU/whatever) cycles.
Although, TBF, you can replace it all with C/C++. Or Rust, assume the optimisation has gotten good enough. It's just that few people are both qualified for and interested in rewriting numerical linear algebra algorithms, and there's no real reason to if the Fortran works.
Everything is just silicon oxide gates being saturated and drained and turned on and off in various patterns very rapidly in a way that means something to us. That Fortran/C/C++/Assembly depends on that tiny two-MOSFET AND gate in the ALU to do the AND correctly every time.
Programming languages at the basic level are just an automated way of putting numbers into a calculator, processing them, and getting another number/status/flag back and doing something else with it based on the result.
Array operations in FORTRAN are much easier for the compiler heavily optimize than it is in c/c++ due to its array model and type system. You can achieve much of the same thing with modern compiler extensions, but it’s difficult and not as portable.