I've posted about it before, but I think the app should have a No-Thumbnail/No-Predownload option like RiF had. Most of the data it uses up I never make use of. It's a big waste.
Connect has a no preload option. Not sure if it works but the toggle is there.
The whole cache buildup has been an issue since it started. I have gotten in the habit of clearing the cache anytime the app seems to slow down. Around once a month or so.
To be fair lots of other apps have a cache buildup issue as well but nothing as severe as connect.