Rust is going to do well on toy examples. This is because in a naive implementation, for each thread, Rust statically allocates enough space for the largest pos

Rust is going to do well on toy examples. This is because in a naive implementation, for each thread, Rust statically allocates enough space for the largest possible stack the thread will need. On a toy example this will be quite small. In real code, some branches will have large futures that will bloat the size of every thread, even if the thread doesn't take the bloated branch. You can mitigate this issue by heap allocating large futures on cold paths, but this requires insight and tuning. Some runtimes can handle this for you, but they come with other performance tradeoffs.