I have played a little with the settings again and I found the cause. You can get stuttering with activated Vsync in Compiz or with "Force fullscreen redraws on repaint". It's a dilemma. With Vsync on tearing is gone and without the second option Compiz has graphical glitches and stuttering. But both of them cause this ugly stuttering in games. Activating Vsync in the Nvidia settings has no effect on Compiz or games.
I have played a little with the settings again and I found the cause. You can get stuttering with activated Vsync in Compiz or with "Force fullscreen redraws on repaint". It's a dilemma. With Vsync on tearing is gone and without the second option Compiz has graphical glitches and stuttering. But both of them cause this ugly stuttering in games. Activating Vsync in the Nvidia settings has no effect on Compiz or games.