That's true, if the Interface Types proposal gets accepted that overhead should be significantly less. At that point it'll get really interesting what the potential performance looks like for DOM-interaction heavy apps.

https://github.com/WebAssembly/interface-types/blob/master/p...

I wouldn't think it's far behind. The Multi-Value proposal, which had huge ramifications, was recently accepted in April so WASM is clipping along at a fair pace still.

https://hacks.mozilla.org/2019/11/multi-value-all-the-wasm/