If you work with many tabs in Firefox, you may have some websites that leech away the computer’s processing power or memory even when they are running in the background. Some websites for instance update contents automatically even if they are running in a background tab, others may play Flash contents like advertisement or videos.
The Firefox add-on Suspend Background Tabs tackles the issue by suspending actions in background tabs. The author of the extension notes that it currently won’t take action on sites with Flash or media contents, but that a future version may introduce the – in my opinion much needed – feature.
Once you have installed the extension in Firefox it works automatically from there on out. This extension works best for users who have dozens of tabs open in the Firefox web browser. If you limit your tabs to less than ten, you will probably not notice a big difference unless your computer is a bit on the low side resource-wise.
The add-on suspends automatic actions by websites, for instance the automatic updating of messages on Twitter or Google Mail, until you activate the tab again. You will notice on these sites that the messages will only get refreshed once you activate the tab again.
It is unfortunate that the extension does not cover Flash related contents as well, as they can draw lots of resources even in the background. While you could deal with the issue differently, for instance by installing NoScript or a Flash blocker, the solution may not be as comfortable and automatic as what Suspend background tabs has to offer.
The Firefox extension comes with an option to not suspend pinned tabs in the browser. I’d like to see an option to whitelist particular domain names so that they won’t be suspended as well. Despite that, it can be an interesting add-on for Firefox users who run many tabs in the browser and notice that Firefox is not as responsive as it should be.
The extension should not be confused with Firefox’s Tabs on Demand feature. Firefox from version 13 on will only load the active tab on startup when session restore is active, and all other open tabs only once they have been selected.
Update: Suspend Background Tabs is no longer available. It is not clear why that is the case and whether it has been pulled by its author or for another reason.
A suitable alternative for it is Suspend Tab, a Firefox add-on that offers very similar functionality. It adds functionality to suspend individual tabs in the front end of the browser and a time out feature to unload tabs automatically after a certain time of inactive has passed (default 30 minutes).
Another option of interest is a whitelist that prevent the suspending of certain sites when they are open in Firefox.
Suspend Tabs handles the unloading of tabs different than other extensions of its kind. It only unloads the tabs contents and fastload caches but not metadata which in turn means that there are fewer side-effects.