Just to clarify, 476kb of WebAssembly != 476kb of JavaScript. Still, your point stands in that wasm-based sites will likely never beat their pure JavaScript counterparts in terms of data transfer; you'll need to make up the increased cost of wasm somewhere else. One place that browsers attempt to make up the difference is in the use of streaming compilers, where the browser can start compiling wasm as it's coming in from the network, whereas with JavaScript browsers have to wait until the entire resource is delivered before the parsing stage can begin.