Hi Dana,
I'm using OS 10.9.4. When clicking on the arrow in the main screen the whole site shudders, it's not a specific item that behaves irregularly. I removed all scroll motion fills and there's a really really subtle shudder. I also removed the icon menus, which have scroll motion so they stick to the top leaving the fill's scroll motion with no success. I you like I could record a small video to show you and send it over dropbox or something like that.
Let me know how I can help you,
Julián