YES! Performance with javascript can approach native code, but it isn't as fast as it yet. In addition, it takes up more system resources (ram/cpu) making it

YES! Performance with javascript can approach native code, but it isn't as fast as it yet. In addition, it takes up more system resources (ram/cpu) making it so that you need more of said resources and more power is drawn (which is especially problematic on mobile devices, where battery is limited). To the extent that it is possible to block ads in a browser, it is also possible to block said ads in a mobile app.