https://github.com/avodonosov/pocl
The unused javascript code can be removed (and loaded on demand). Although I am not sure how valuable that would be for the world. It only saves network traffic, parsing time and some browser memory for compiled code. But js traffic in the Internet is neglidgible comparing to, say, video and images. Will the user experience be signifiqanty better if browser is the saved from the unnesessary js parsing? I don't know of a good way to measure that.