We support low-end devices well (although this is a constant balancing act)! Bevy runs well on iOS currently (and we have WIP Android support ... we're working on re-enabling that asap). Fans spinning is a known issue, but it is generally decoupled from framerates (which tend to be fine). On some machines we are over-engaging cores, even with empty apps that do nothing ... my current theory is that we need to adjust how our task pools are managed.