Did you try running the game in Software mode, rather than Direct3D? That is set in the configuration program; there should be a shortcut in the start menu folder for the game, or you can start it directly from the configtool.exe program in the Divine Divinity install folder.
Did you try changing the resolution, to see if that made a difference?
Maybe forcing a lower FPS limit would make the game smoother?
Someone who ran into a problem with the game speed (
Game Too Fast) used this as a fix (
FPS Limiter Universal: Stabilize the performance of your games), and in Divinity 2 lowering the FPS cap could help some people who had issues with performance or animation stuttering. Neither of those match your situation, but it might be worth a shot, anyway.
Another thing that could help in Divinity 2 was in the nvidia control panel to set the number of frames to render ahead to zero for the game.