Why is this code slow?

[matheus]

On Sunday, 24 March 2024 at 19:31:19 UTC, Csaba wrote:
> ...
>
> Here are the results:
>
> C: 0.04s
> Python: 0.33s
> D: 0.73s
> 
> ...

I think a few things can be going on, but one way to go is trying 
using optimization flags like "-O2", and run again.

But anyway, looking through Assembly generated:

C: https://godbolt.org/z/45Kn1W93b
D: https://godbolt.org/z/Ghr3fqaTW

The Leibniz's function is very close each other, except for one 
thing, the "pow" function on D side. It's a template, maybe you 
should start from there, in fact I'd try the pow from C to see 
what happens.

Matheus.