We don't need JS to get 2% more faster, the limits of those speed improvements were reached, web assembly combined with a compiled language could offer more speed.
I would like to see Firefox move faster in implementing good web APIs, like the lazy loading of images, push for HTML and CSS improvements(like let me customize the numeric text input arrows with css instead of forcing me to use a JS library) .
Maybe the Rust rewrite will make Firefox better achitected so you could have a node version based on Mozilla technologies or you could easily use the web assembly VM in your application without having to load the full Chrome code.
