I haven't been following WASM progress, do people generally share this optimism for WASM performance improvement over time, relative to JS? I was under the vague impression that all the "obvious" optimizations had already been done (i.e. JIT, and more recently, SIMD support)
As an example, looking at the in-the-box Garbage Collection support that's being flushed out, as an example will improve languages that rely on GC (C#, Java, Go, etc) without having to include an implementation for the runtime.
Another point where there's potential for massive gains are the browser UI interop as well, and I think there's been a lot of effort to work within/around current limitations, but obviously there's room to improve.
However, the new proposal for reference types that we split off from the GC proposal tries to give a more nuanced answer to that. It introduces reference types without any functionality for allocating anything within Wasm itself. In an embedding where host references are garbage-collected that still requires a Wasm implementation to understand GC. But in other embeddings it does not need to.”
Aren’t threads still missing? That seems like a pretty major optimization, now that almost any CPU you can buy has multiple cores.
That said I think in the browser something like emscripten can do something akin to "use web workers with shared array buffers" to back it all up so that threading APIs roughly work, but yes, WASI currently has nothing for this.