[azakai]

That 2x figure is something that shows up consistently over the years, since asm.js in fact. The 10x cases are rare, like they found. Still, 2x is enough to justify using a different language in some cases.

Separately, though, on very large applications wasm does have an advantage on startup times: there is no warmup period as the JIT learns the types, no sluggish first frames for the entire application or the first time you click on a feature that hits a new code path. For something like Photoshop or a game engine that can be a very big deal. But, again, this type of application is not the most common, so JS will remain the best option for most things.