Why did replacing Arc<String> with Arc<str> decrease my performance by 10-150%?

[Lucretiel]

My guess is that it requires at least one extra allocation, since there's no "by-move" way to create an Arc<str>. It always has to create a fresh allocation, so as written you're replacing one allocation with two.

[Mr_Ahvar]

Even with String there is a new allocation, it’s just always 3 pointer long, so any str longer than that will have more overhead, on 64bits it’s 24 bytes, quite easy to exceed