When I use Firefox I often have many tabs and many windows open (even more so now that they have panorama). I often use the session restore feature because I don't want to loose all my open windows when installing a new add on or restarting my computer for updates. However, with so many tabs open it takes a really, really long time for Firefox to load all the tabs. I'm looking for an extension that will open a place holder tab for all of the websites on session restore but won't actually load the page until I click on that tab to bring it to focus. Basically it would like like I had 40 tabs open but until I click on that tab it won't be taking up any more memory than an about:blank page.


2 Answers 2


You could use BarTab, but I find it doesn't work too well with Firefox 4/5.

Another more reliable way is to use the new about:config property, browser.sessionstore.max_concurrent_tabs.

Go to about:config in firefox and search for browser.sessionstore.max_concurrent_tabs. Set the integer value to 0.

Now when you start up Firefox, only the first open tab will be opened. All the rest need to be clicked/focused on before they are actually loaded.

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  • and also now with the Tab groups feature, FF only loads active tab group.
    – Reddy
    Sep 5, 2011 at 12:11

Bartab will do this.

BarTab can intercept when tabs are loaded in the background or restored after a browser restart and will only load the content when the tab is actually visited. It also allows you to free memory by unloading already loaded tabs, either manually or automatically.

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