[DarthGhandi]

Just going off what I remember from when async started to stabilise, see the top comment on this reddit thread. It may be be fixed by now or simply just allocated memory instead but many were commenting on it at the time.

https://old.reddit.com/r/rust/comments/cych6a/async_performa...

[aliceryhl]

There was a bug regarding the size of async functions growing exponentially in certain cases at some point, but it should have been fixed now.