I'm not sure if this is only in beta but....
I was scrolling the ESV and notice that it get's really hung up on re-finding it's place in the interlinear panel....it has to wait to "hightlight" the center word in the panel, and the main body of the text before it will settle down....
I turned off the interlinear panel to scroll and it was very fast and responsive...
Has it always tried to "find it's place" in the current page?
I had thought that it wouldn't do that....until you clicked on a particular word.....