Firefox browser automatically suspends unused tabs when the available memory is less than 400 MB, the current version 67 has the feature enabled by default and is unloading tabs that haven’t been used for while when memory threshold is low. Mozilla now in a hurry to turn this off as they realized there is a flaw in their low memory detection mechanism, the company will soon (via Normandy) is going to flip this pref browser.tabs.unloadOnLowMemory to false to release users.
We’ve reported about the tabs suspending feature in Firefox 67 and also covered there could be a bug that causing Firefox to discard tabs even if free memory available is in GBs and how to prevent that from happening.
In a newly filed -“tabs are suspending above the low memory threshold”- bug, Mozilla engineer Gabriele Svelto agrees their low memory detection on Windows is somewhat wrong and says to turn off the feature. “Our low memory detection is flawed. I am not sure if this is due to a recent change in Windows or if it always worked this way”.
“In the meantime, I think we should turn off tab unloading on release (it can be done via a pref). I don’t know how widespread the issue is but better safe than sorry”
They’re on it, created a new bug for that, the feature will return in future when Mozilla is sure of their low memory detection logic.
Meanwhile, if you’ve noticed your tabs being suspended even if there is plenty of free memory available, visit about:config, agree to the warning displayed on the screen.
1. Find pref browser.tabs.unloadOnLowMemory
2. Change its value to “false.”
Mozilla will do this automatically to release users via remotely by using Normandy system.
Did this myself as I have Normandy system disabled