This is well beyond any getting used to, is there any way to fix the insane mouse lag?
VSync is automatically on and can't be disabled from within the game. This not only reduces FPS, it also introduces mouse lag. To disable VSync in Skyrim, add iPresentInterval=0 to the bottom of the [Display] section of the Skyrim.ini file in the \Users\[Username]\My Documents\My Games\Skyrim directory.
Source: http://www.tweakguides.com/