[laurencerowe]

While WebAssembly definitely has advantages in terms of faster startup time, throughput is the same order of magnitude as equivalent JavaScript, perhaps 30% faster unless you are using WebAssembly only features like SIMD.

Of course the big advantage from using a language designed for lower level work is that you are far less likely to hit performance pitfalls. But if you write JavaScript as if it were C you tend to get very good performance.

I am sceptical that SPy will manage to beat JavaScript performance wise on average. But I'm interested to see how they do in part because of their learnings could make JavaScript in WebAssembly faster. (WebAssembly has much faster startup than JS which makes per request isolation practical if JS in WASM gets fast enough.)