I think Tumblr does a thing where it loads and unloads elements/posts on the dashboard as you scroll around.

Because holy shit is it buggy. If you scroll past a long vertical photoset, it “unloads” and you are suddenly shot down a few posts. Then you scroll up to see what you missed and the long photoset reloads and shoots you way back up again in a vicious cycle.

Come on, now. :T