The language seems rather complete [L], which makes me wonder: would that byte interpreter be of any use in other environments? How fast is it compared to e.g. V8 and JavaScriptCore? And to µPython?
It should about the same as uPython. There is a few more tricks we can play due to whole program compilation but I don't think we take advantage of that yet.
[L] https://microsoft.github.io/devicescript/language