Er, when it comes to concurrency, non-determinism is usually cheaper than determinism. As soon as you care about ordering, you almost always have to synchronize, and that has a cost.

Austin Clements (of the Go runtime team) wrote a paper that explores this in detail [1]. That was before joining the Go team, but the concepts are universal.

[1] https://people.csail.mit.edu/nickolai/papers/clements-sc.pdf