[garren]

I was going to suggest introducing the kind of heuristic analysis found in antivirus engines. Kind of like your item #2 - don’t run scripts that behave badly (for some heuristically recognizable “bad behavior”.) Basically a browser built-in AV scanner. Maybe give a user the option to permit the script once per session, or forever. Something like this would definitely introduce a UX speed bump, it sounds terrible.