Recently, I just read this article https://developers.google.com/web/updates/2017/12/audio-worklet .
Although I don't fully understand what is written on it, but it looks like a very nice improvement for web audio performance.
How will it affect libopenmpt.js performance on web?
As far as I understand it, it will probably help, if used correctly from the JavaScript side.
libopenmpt itself is not directly concerned with how it is used from JavaScript, of course.
However, it might make sense for us to update chiptune2.js with Audio Worklet support, as it kind of serves as an example on how to use libopenmpt from JavaScript.