I'm using Firefox 57.0 on Ubuntu 16.04 amd64. I am firefox user since 2007. I love Firefox, but lately there are some things that annoy me after upgrading to Firefox Quantum. Firefox is too expensive to use bandwidth when in use. From the screenshots I have included, I just opened Facebook in mobile mode, I see the source code (CTRL + U) the page does not have any javascript that allows background activity. When I finish opening a page, Firefox still using full bandwidth to retrieve data from the internet, I do not know exactly what is going on, I just monitor it using another program. For unlimited internet quota users this might not be too distracting, but not with me, I use quota based internet packages. What does Firefox do when using too much bandwidth? Can I turn off this feature? I just using nload and tcptrack at this case.