Unnormal shaking when moving the background

hi all,

I’m working with a 2D platform running game, in which the role would run from left to right.
To archive a infinite background, I used 10 CCTMXTiledMaps as my random background, and I use CCRepeatForever action to let them move left.

but somehow, when the game is going, I would see the screen or the maps shakes, but not all the time.

Can anyone tell me how to solve this? Thanks in advance.

What is your frame rate and CPU load doing the shake?