If you compile the Rust example with optimization (-O) it just throws the result away, which gives the ~0.030 time chrisdouay found. However, if you add a prin

If you compile the Rust example with optimization (-O) it just throws the result away, which gives the ~0.030 time chrisdouay found. However, if you add a println!() around it, it has to calculate the result. Here's the running time: > time ./fib 1134903170 real 0m2.242s user 0m2.240s sys 0m0.000s I tried the C example as well (with -O2) and found this: > time ./cfib 1134903170 real 0m4.671s user 0m4.670s sys 0m0.000s So.. which one is faster again? This "comparison" unfortunately seems too naïve to not be on purpose - no analysis, no real discussion, not even some reasoning about the defaults and why the big difference in numbers. It seems to be just looking for views/comments (even if negative) without any intention to produce real content. What worries me are the ones that will take this for a real benchmark and just "share on facebook" and spread more disinformation.