[renshaw]

I should note that the Rust version currently omits some features of the C++ version, such as read-limiting and the actual counting of the throughput. These things are cheap, but they may explain why Rust is faster in that one case.

[pcwalton]

We did some benchmarking on IRC today in light of this post and we found that Rust's stdio is currently quite slow due to a flag not being set properly in libuv which causes it to punt to a thread pool. There is currently a fix in the queue: https://github.com/mozilla/rust/pull/10558

[srean]

In case you get some time would appreciate a blog post or a comment describing what the issue was on the rust side as well as on the libuv side. Upvoted in advance.