I think that optimization should still work when using Wasm, unless the Wasm code does something silly like manually pump the stream (read from one, write to th

I think that optimization should still work when using Wasm, unless the Wasm code does something silly like manually pump the stream (read from one, write to the other), but I think you'd have to go out of your way to do that, and anyway the same is true of pure-JavaScript code.