This addon suspends background tabs to save the memory.
There are some existing addons for this purpose. However, this is defferent from others on the point: 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.)
Other similar addons overwrites tab state or close the original tab after duplication, so they can break other tab related addons like Tree Style Tab. This is started to be developed to solve such compatibility issues.
Similar or Related Extensions
I cannot trust such an addon which calls internal APIs. Is there any other alternatives which is based on stable/public APIs?
Dormancy and UnloadTab suspend tabs via public APIs, so they are often stabler than this addon.
I hope to save my CPU resources instead of the memory.
Released version includes following language packs:
There is the updating history and the list of known problems.
Don't select pending tab after suspending of the current tab, if possible.
Respect preferences for visibility of "Suspend Other Items" menu items.
Works on Nightly 47.0a1.
Add "Don't suspend this site automatically" to the tab context menu.
Detect host name of web pages more correctly.
Visibility options for menu items work correctly.
Next focused tab after the current tab is suspended is now configurable.
Newly opened background tabs can be suspended by default.
Features are available from the context menu on the contents area.
Provide ability to limit the number of on-memory tabs.
Works on Firefox 29 and Nightly 32.0a1.
Drop support for Firefox 25, 26, 27 and 28.
Works on Firefox 25 and later.
Fixed: Background tabs are suspended correctly after a while, even if there is no exception. (by YosukeM, thanks!)
Modified: Just to pass through AMO Editor's review, make codes free from "evalInSandbox()" and E4X. They were still there only for backward compatibilities so they never caused errors/security issues on lately Firefox, however, editors persecutive rejected those codes, then I've given up and removed them.
Modified: Some codes depending on "evalInSandbox()" are just removed. AMO Editors always banned new releases, because an included library had codes with "evalInSandbox()" for backward compatibility - even if it is NEVER called on this addon.