Does anyone have this issue were firefox becomes slow if left open for a long time. In my case after a couple of weeks rendering becomes slow and when I use youtube for example if is laggy, just trying to change volume taka few second to show the volume bar. It also happens to my laptop at work. I have around 30 tabs open.
So perhaps another anecdote is in order. I currently running three instances of Firefox (different profiles) on a low-end Celeron laptop. I don’t usually shut them except sometimes by mistake. What I do do is close tabs, if only for simplicity’s sake (because idle tabs are unloaded from memory anyway). I’m experiencing no sluggishness issues.