To add to this comment, Stopify is a JS-to-JS compiler that instruments sync JS code to make them interruptible at set points. The paper [0] can explain it better than I ever could.
I work on an experimental Pyret [1] runtime that uses Stopify to instrument compiled Pyret code (plain old JS) so that we can run Pyret code on the main page thread without hanging it up. Main thread execution is important for quick/easy DOM access. In terms of performance cost, we haven't measured too extensively, but so far, on average, we're seeing a 2x slow down compared to un-Stopified programs.
I work on an experimental Pyret [1] runtime that uses Stopify to instrument compiled Pyret code (plain old JS) so that we can run Pyret code on the main page thread without hanging it up. Main thread execution is important for quick/easy DOM access. In terms of performance cost, we haven't measured too extensively, but so far, on average, we're seeing a 2x slow down compared to un-Stopified programs.
(Disclaimer: paid contributor for Pyret).
[0] https://www.stopify.org/research.html
[1] https://www.pyret.org/