To add to that, the big advantage of AngelScript is that there's a low barrier to entry. Anyone can write a simple script, even if it's just to change a palette gradient or adjust layer speeds. There's no boilerplate, nothing needs to be compiled, testing is a matter of saving and running. That's obviously less the case for C++ plugins. I'm sure there is a use case somewhere out there, but JJ2 is a small game. It seems more worthwhile to work on the plugin system that everyone can use, even if there are some small trade offs.

On that topic, is there anything specific you're thinking of here? Anything you've wanted to make that AngelScript is too slow or limited for? People have written MOD players and (as seen above) JJ1 emulators in it that ran at acceptable speeds, so the speed hit isn't that great. Maybe what you're trying to do - whatever it is - can be done with some optimisation?