Оказывается, у всяких интерактивно-рекламных пидоров есть способ обойти dom.min_background_timeout_value: > Firefox 50 no longer throttles background tabs if a Web Audio API AudioContext is actively playing sound. Firefox 51 further amends this such that background tabs are no longer throttled if an AudioContext is present in the tab at all, even if no sound is being played. These resolve a number of issues with apps which play note-based music not being able to time or synchronize the music properly when the tab is in the background.