Firefox memory usage with Facebook
After using Facebook Watch on Windows 10 for a while, Process Explorer will show one Firefox Process with a huge amount of memory, which takes up to two minutes of high processor usage to be released once the tab is closed. This slows work with the other Firefox tabs. Firefox Task Manager "forgets" about it as soon as the tab is closed. This does not happen on Android.
This problem has been around for a long time. Just thought I'd see if anyone has any ideas other than not watch FB videos.