if you have the habit of opening many tabs in the background and does not want to hurt the current page you are loading, then here is a nice addon for Firefox will load the cards one by one making sure the Internet connection is not is flooded and thus allowing you to browse the new pages, without stopping, while the card background is loaded.
This addon is very useful for people who are having slow Internet speeds. As the name suggests Tabs progressively load addons to load the tabs of background, one after another and you can navigate without problems.
You can set the maximum number of cards to be loaded simultaneously, the maximum number of beds tabs loaded, the next card to recharge etc.
You can set the maximum load value card competitors based on connection speed and based on current requirements. If you are downloading any other file then you could give a little value in there and if your Internet connection has more speed then setting the highest value will not be a problem.