It used to be waaaay more expensive and has gotten much better now. But it still costs, all I know is, that when I do 600 raycasts each, it costs me around 8 ms on medium hardware. Batching it reduces the cost to 2 ms for me. For simple things like GetPosition I did not noticed a perf hit, but for getting vertices I also did. So mid term, I will batch all often used calls into wasm. For now raycasting was the biggest bottleneck.