First, at least in full screen low res mode, the first time you launch a game, after the loading screen, the layout appears on screen for a moment before MAME is loaded. A workaround for this is a script that loads MAME hidden and quits it inmediatly. This is what I'm using, but it means some additional seconds of delay in my boot process.
Second, after switching orientation, if you're in the top position of the gamelist, the first game doesn't show its snapshot. My solution is to to add a name called 0000 with no data to mame.xml and with black snapshots, so it will be the first game. It's not perfect but I prefer a blank space than a game without snapshot.
I would try it myself, but the download page is not working.