Go's async story is great, as there is no function coloring at all. That being said, I don't like Go's syntax very much. The runtime is great though.

To be fair, Go’s async story only works because there’s a prologue compiled into every single function that says “before I execute this function, should another goroutine run instead?” and you pay that cost on every function call. (Granted, that prologue is also used for other features like GC checks and stack size guards, but the point still stands.) Languages that aspire to having zero-cost abstractions can’t make that kind of decision, and so you get function coloring.

I'm not sure this is 100% correct. I haven't researched it but why would they perform such a check at runtime if it is 1)material and 2) can be done at compile time. However, even if it is, Go is only trying to be medium fast / efficient in the same realm as its garbage collected peers (Java and C#).

If you want to look at Rust peer languages though, I do think the direction the Zig team is heading with 0.16 looks like a good direction to me.