I've had this happen a few times already. If I leave a lemmy tab open and do something else after a certain amount of time, I find my system starts to bog down. After checking task manager I find that all system memory is being used up by my browser(Firefox). Never had this issue until this week. I think this issue is related to how new posts keep loading in the feed.
I don't know if this is just lemmy not working with Firefox or a lemmy specific issue.
I didn't look too deeply at it, but I'm presuming the setup using websockets pulling live post data is just building up a massive dump of html over time. Would probably be better to handle how scrolling and post data works so that the tab isn't just an ever growing dataset if the window is left open, have it flush away old posts and only retain ~200 in the live feed.
I could be completely wrong with this though as I haven't looked at how lemmy works under the hood.
I'm seeing the same thing, also in Firefox but I suspect it'll happen on any browser. I'm with you, I think it's because it keeps loading in new posts but doesn't unload the old ones. It's probably an easy fix