This is failing because of using nightly test feature (for bench functionality). Should we allow this or should we use something else, maybe criterion? Or is there another way?

To avoid this problem, create a new benches folder in which you put the benches. There you can put the #![feature(test)]. Done this way, the crate itself won't require nightly to build so all good. :)

This is great, thanks a lot! Now summoning someone who can actually merge. XD

cc @Urgau

Looks fine to me, but didn't do a deep dive into all the benches, I trust @GuillaumeGomez did it.

One tough: it would be good to check those benches in CI.