alt Hacker NewsThings might be getting better for JS, but just looking over those briefly, they don't look memory constrained, which is the main place where I've seen significant speedups. Also, simpler code makes JIT optimizations look better, but that level of performance won't be consistent in real world code.
You might be right in your use case, but still, JS is not the benchmark to beat. Native Client was already almost as fast as native code, started up almost instantly, and didn't get a decade of engineering with who knows how much money behind it invested into it.
Webassembly that was supposed to replace it needs to be at least as good, that was the promise. We're a decade in, and still Wasm is nowhere near while it has accumulated an insane amount of engineering complexity in its compiler, and its ability to run native apps without tons of constraints and modifications is still meh as is the performance.