This is precisely why I like Fever as an RSS reader. Fever lets you separate feeds into low-volume kindling and high-volume sparks. Kindling are the feeds you want to keep up with regularly, while items that are mentioned across Sparks bubble up to the top (Its like having your own personal Hacker News).
Well, I'd say any reader with some kind of categorization support (tags, folders, etc) lets you do that.
I have folders in Tiny Tiny RSS that never accumulate more than a couple of unread items, and I have a folder with 22000 unread items, it works just fine.
