zica,
It seems that when your browser is at the top of the Twitter feed, it will continue to refresh, regardless of your settings. I suspect that you can avoid that by scrolling down a tweet or two (this works for me in Tweetdeck on Chrome).
On reloading a Twitter page which has been dormant for a while,
a Reddit thread suggests convincingly that this is because Firefox remove dormant tabs from memory:
Quote:
Originally Posted by justausername22222
It's a side effect of a Firefox (not twitter.com) feature that's designed to save RAM on tabs you're not actively using.
I think you can turn it off by setting browser.tabs.unloadOnLowMemory to false in about:config
(On Android the setting is apparently called browser.tabs.disableBackgroundZombification but the source I found this from is a few years old)
