Not sure if you're familiar with or heard about AssemblyScript [1]. It sounds like the goal you are trying to achieve, but with a saner approach: create a TypeScript-like language that compiles to WebAssembly. This means it gives you native access to SIMD, and eventually even threads! All while avoiding the overhead of learning a new language (well there are still some gotchas since it is actually a new language, but very close). No need to think about whether you need to optimize X function or manually manage memory somewhere, and still get the awesome performance of Wasm.

[1]: https://www.assemblyscript.org/