How can I unload a tab manually?

Question

Firefox has a setting "Don't load tabs until selected" (see How do I make Firefox 13 Load All My Tabs on Startup or when Resuming Reload). I like that behaviour.

I am searching for a way to "deload"/deactivate a tab manually for a session (until I reload it).

It should stop all running JavaScript functions and plugins (like Flash). The whole webpage content may disappear until I reload/re-activate the tab, but that is not a requirement. The title has to be displayed as tab label (like it is the case with the startup setting, too).

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The workaround would be to restart Firefox and don't switch to the tab I want to be deactivated. This is pretty annoying, of course.

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EDIT: Here is what I found so far

• BarTab
  • no longer being maintained (see why)
• BarTab Lite
  • (thanks, @bytebuster)
  • seems to miss this functionality from BarTab
• Dormancy
  • experimental; comes with warning that it "may eat your session"
• Suspend background tabs
  • (thanks, @Greck)
  • experimental; is not exactly what I'm looking for, but could be an alternative (doesn't disable videso/Flash, though)
• Tab Mix Plus
  • Feature request: Unload Tab feature
• Tab Utilites
  • (thanks, @bytebuster)
  • seems to offer this functionality only for automatic unloading
  • Feature request: Add "unload tab" to tab context menu.
• UnloadTab
  • removed from addons.mozilla.org (who knows why)

Answer 1

In one of the links you referenced at Tab Utilities: Feature Request, there is already an answer from the developer (scroll down to comment no. 4) on how to do this. The answer is to:

• Add the Restart Tab item to the context menu.

Why it's called "Restart Tab" and not "Unload Tab", I don't understand, but he says you can just change it if you want. Set:

• extensions.tabutils.menu.context_restartTab.label to "Unload Tab".

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By the way, at the moment it only works on tabs that are not selected/focussed. In other words, if you do "Restart Tab" on the currently open tab, it will just reload. You have to switch to another tab, then right-click on the tab you want to unload, and choose "Restart Tab".

Here are the instructions from the developer, I updated them a little:

1. Set browser.sessionstore.max_concurrent_tabs to 0 in about:config. (BarTab Lite or Load Tabs Progressively extension should also work.) [ the above is outdated, in current versions of Firefox, go to preferences/options for Tabs, and check "Don't load tabs until selected". ]

2. Unload tabs manually with Restart Tab or Restart All Tabs menuitem. [ first you have to make sure the "Restart Tab" item is added to the context menu, in Tab Utilities preferences/options -> Appearance -> Menus -> Tab Context Menu ]

3. Unload tabs automatically after a specified period of inactivity with extensions.tabutils.restartAfter option (minutes).

4. Tag bookmarks with "norestart" to make an auto-unload black list.

Answer 2

A workaround: Force the tab to reload using CTRL+F5 and stop it quickly (using the cross in the URL bar). It may leave you with a blank page (or almost blank) which consumes little resources.

Answer 3

All Tabs Helper and Auto Unload Tab do this, among other things.

Answer 4

As of December 2018 the Auto Tab Discard addon appears to be a great option.

The source code is available at https://github.com/rNeomy/auto-tab-discard.

Answer 5

https://addons.mozilla.org/en-US/firefox/addon/unload-tabs/

New (Sept 2019) solution that seems to get around the issues that killed earlier addons that provided this feature.

Answer 6

One option would be to use built in Task Manager. If can be accessed from application menu More tools > Task Manager or by pressing SHIFT+ESC. It lists all the tabs along with memory and CPU usage. You can press X button next to each tab to unload that tab.

Official support page: https://mzl.la/3zFKujy

Answer 7

Firefox provides the about:unloads page for information about memory-freeing tab-unloading priorities. You can use this page to free them in that order.

Depending on your use case, because the priority is given, it may be viable to unload all [you don't need], or unload what you haven't opened the longest.

Unfortunately, it does not allow you to unload a specific, self-chosen tab.

To open the Tab Unloading page enter about:unloads in the address bar and press enter.

Answer 8

There is the extension BarTab Lite X. This is a light extension. Its feature for unloading tab works with recent Firefoxes.

However, better check that unloaded tabs don't mess up Firefox' session restore.

Answer 9

If you have e10s enabled, taskkill /f /im plugin-container.exe or your OS equivalent is a pretty easy solution.

Firefox will think the content process has crashed, but that is wrong.

Clicking on a tab will reload it.

Answer 10

I was searching for a why to freeze the current state of a tab, so maybe these two addons might be helpful for you too:

Freeze, Tab Suspender

Discard tab

"Unloading" was announced by a users comment, and searching that let to these results:

Unload tab (experimental, exactly what you wish, set on a state like on startup)

Unload tabs (all, or all but current)

Answer 11

I can recommend the Add-On 'Tab unloader'.
It seems to work well (so far, I only installed it 2 hours ago).