One thing I would love personally is the ability to restrict JS usage to a CPU limit, which increases in response to certain events and gradually reduces to 0 i

One thing I would love personally is the ability to restrict JS usage to a CPU limit, which increases in response to certain events and gradually reduces to 0 if unused. This could be * A number of seconds on page load, * a fraction of a second in response to network activity (eg. image loads), * a small number of frames in response to significant user interaction (mouse clicks, typing), * one frame after less-significant user interaction (mouse movement), limited only to local operations (no network activity). The vast majority of sites should need nothing more than this, so opt-in to unlimited usage should be fine. Sites where the user has enabled extra permissions like notifications should be allowed extra time for those.