Tabbed browsing has given multi-tasking a whole new meaning, but it can also bring your entire computer to the knees if you do not keep check on the tabs you’ve opened. Often, a single rogue tab is enough to bring the browser to a standstill. Even without any runaway scripts, too many tabs will slow down the performance of the browser making web surfing sluggish and unresponsive. A cure for this is to prevent background tabs from using too many resources unless needed.
Previously, we wrote about a unique feature that Firefox has that prevent tabs from loading in the background until selected by the user. This is useful if you have configured Firefox to automatically load tabs from the last session at startup, or when you load a previously saved browsing session into memory. However, once the tab is loaded, it will continue to consume resources in the background even if it’s not the active tab.
Suspend Tab is an add-on for Firefox that totally suspends all activities in background tabs. This causes the browser to release valuable system resources making it more responsive to user inputs. Tabs can be suspended from the context menu, or automatically suspended after a certain period of time has elapsed. A whitelist is provided to prevent certain tabs from suspending.
The add-on author explains some key differences that exist between this add-on and similar ones, such as “Suspend background tabs”, which remains currently removed from Mozilla’s add-on website.
…this addon unloads only the current contents and fastload caches for "Back"/"Forward", so it don't break metadata related to tabs and provides ability to suspend/restore tabs with less side effects. (On the other hand, because this addon calls very unstable/internal APIs of Firefox itself, this can be disabled by Firefox's update in the future.)
A tab can be restored by clicking anywhere on the page when it is needed. There is also a whitelist facility to avoid automatic suspension of certain pages.