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Comment by FabHK | Hacker News Reader

A few observations:

- on my machine, C++ is slower than C.

- I thought that in Julia, startup and compile time could be a factor, but they're pretty negligible (maybe 1 to 5% or so of the runtime, for Julia 0.7).

- Without the -O3 switch, the runtime more or less doubles for C and C++, making these languages slower than Swift, Go, Java, Dart, Julia, etc. That surprised me.

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The -O3 switch removes a recursive call, among other things (https://godbolt.org/z/oS3Cju).

Interesting. (Awesome compiler explorer website, btw).

The Julia version (whose runtime is halfway between the C versions with vs without -O3) contains both recursive calls, FWIW.

Yeah, startup and compilation time in Julia is not a big deal. One could even make the compiler work a bit harder, but you would have to ask a lawyer if this still counts as recursion ;-)

    julia> function fib(::Val{n}) where n
               if n <= 1 return 1 end
               return fib(Val(n - 1)) + fib(Val(n - 2))
           end
    julia> fib(n) = fib(Val(n))
    julia> @time fib(46) # Compilation and execution
       0.095409 seconds

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