This is starting to really frustrate me now!
When applying a background to my phone, weather it be from the Gallery or integrated wallpapers, sometimes it will jump around on the homescreen. For example I will be in an app, press the home button and on going to the home screen the wallpaper will momentarily zoom in then zoom back out to normal. As this is happening the phone has excessive lag.
I've tried to isolate the issue, thought it might be a bad factory reset but my sister is over this weekend and hers is the same! it doesn't happen when running any applications in particular, it's literally random but when it starts doing it it will keep doing it. Restarting the phone doesn't fix.