Created attachment 8772946 [details] screenshot.png User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:47.0) Gecko/20100101 Firefox/47.0 Build ID: 20160606114238 Steps to reproduce: Open a "random" (bad-designed) web page. Actual results: Many web pages are really poorly designed redrawing the DOM for nonsense/unuseful things wasting CPU cicles and slowing down/blocking Firefox. For example the HTML5 music player from Google Play wastes up to 40% of my Core-i7 CPU while updating the progress bar (a thin orange bar moving left to right while playing) and a small icon. Expected results: Firefox must continue to work normally. An option (button?) must me available to allow users indicate when they want to ignore DOM updates for a given page once the initial DOM is already displayed, (warning the user that this can break some pages) and so "punishing" bad designed pages instead of "punishing" final users. (DOM can automatically be re-enabled when Firefox detect user-input on the page).
Comment on attachment 8772946 [details] screenshot.png example of poorly designed web page consuming 40% of (Intel Core-i7) CPU while just redrawing the progress bar and an icon.