mod_display: page updates reload the entire conversation.
There have been a number of changes to the way page updates happen and I'm not sure when this broke, but mod_display now reloads the entire conversation on every server refresh. If you're reading comments in the middle the scroll position is lost and you need to find it again - every 'n' seconds. The pause control (shift+pause) can avoid this but a better approach would be to update the conversation only if something has changed; which I believe was the behaviour once upon a time.
I may or may not have time to look into this in the coming weeks so leaving here so as not to let it fall through the cracks.