There is not much overhead with Rust iterators at all. They are essentially concrete versions of the deforestation that Haskell can do to avoid constructing int

There is not much overhead with Rust iterators at all. They are essentially concrete versions of the deforestation that Haskell can do to avoid constructing intermediate lists, and compile to code that is close to the equivalent C (the functionality is all statically dispatched, so the compiler can inline and optimise the calls). This is a case of having experience with and trusting one's tools. I wrote a blog post a while ago that used iterators heavily http://huonw.github.io/blog/2014/06/comparing-knn-in-rust/ http://huonw.github.io/blog/2014/06/comparing-knn-in-rust/ , as you can see the performance is good.