Calling a short function is generally a poor idea, to be honest. You want significant execution time on either side of the bridge, not constant boundary crossing.
The thing is that I had expectations of why the boundary crossing was so slow. I expected a no-heap WASM function that returns a simple value to be pretty fast, but as the other comment points out the "boundary" in this case might not be the WASM/JS boundary so much as the inability to inline WASM.
Not really. Unless it's called quite often. Premature optimization is not a good thing in general. Find your bottlenecks, code for correctness and ease of understanding first and use optimization if it's basically "free" and don't worry much about it otherwise.
