Written by: Andrew Connelly
Starting with Firefox version 67 (now on Version 69), Firefox now contains a feature that allows users to optimize the way memory is used. Some machines with low memory begin to experience performance issues once many applications are in use. Browser applications can contribute to these issues as more tabs are opened.
Firefox now allows the system to automatically decrease the memory usage should the computer require more resources by “unloading” the tabs in the background, leaving only the active tab loaded in memory. To take advantage of this, all you need to do is turn this feature on!
In any Firefox tab, type the following: about:config
Then, in the search bar immediately below, type: lowmemory
That search term will find a feature called “browser.tabs.unloadOnLowMemory”. By default, it is off (or “false”).
Right click the feature and click Toggle. This will turn on the Unload Tabs feature.