Impact Winter on laptop

I've got a laptop with these specs: Core i3 2310M/8GB DDR3 1333/GT555M 2GB

I barely get 25FPS in 720p with lowest shadows setting and less than 20 FPS in 1080p on external monitor. Is it my laptop or just game optimized really bad? If anyone here tried to play the game on similar hardware, how's the game was performing for you?