So, after using firefox in the background to browse websites or watch videos I checked my memory usage in firefox with about:memory -> Measure and saw that youtube was consuming a decent amount >2GB (checked the main url when clicking the youtube src, it was the video on that sole tab i was watching and nothing else playing youtube in the bg) so i closed that tab, waited a bit and re-measured but then see that the memory usage for youtube rose about 200MB... and the website for youtube is that same url for the tab that i just closed (when checking the src in the results for Measure). I've been revisiting the about:memory page, reloaded it and re-Measured and youtube is STILL THERE. Even now, 10 minutes later i still see youtube there, with none of my tabs running youtube. If i close firefox entirely and re-open my tabs then it'll very likely fix it but this has to be a major issue no? I shouldn't have to close the entire browser program just to fix a website visit, which is youtube of all websites. As of this moment, firefox, with 8 tabs open, is consuming 4,452.99MB (~4.5GB) where 2.5GB is youtube for that page i closed. I don't know if sharing memory reports from the about:memory page give my cookies away or leave me open to a similar vulnerability so I won't share it unless a dev or similar asks for it but for now, I've included an image showing all the tabs i have open on firefox, 2 windows.