If available it's better to use instantiateStreaming [0] for faster compilation, e.g. this:

    fetch('../out/main.wasm').then(response =>
      response.arrayBuffer()
    ).then(bytes => WebAssembly.instantiate(bytes))

could be expressed as this:

    fetch('../out/main.wasm').then(response =>
     WebAssembly.instantiateStreaming(response))

[0]: https://hacks.mozilla.org/2018/01/making-webassembly-even-fa...