I tried to get a video of this but my phone wouldn't screen record.  Whenever I'm at the main menu or when I save & quit my game, the frames drop extremely low.  I don't know what the frame rate is, but it drops way lower than 1 frame per second (maybe about 1 frame every 5 seconds (terrible!)).  It makes having to load a world, delete world, copy a world, change settings, view the marketplace, etc. a huge burden & playing the waiting game to do anything.  There are no issues with FPS while playing or after a world is loaded, however.  Somehow (& only sometimes) after hours of playing when I save & quit, the main menu will go back to normal, but I don't have an idea on how or why it fixes itself.  But if I close the game & start it up again, it goes right back to very bad frames.