Basically the Outdoor sequences will take a lot of pressure on the Graphics card as it has to Draw multiple textures but as soon as you Go indoors it might get a little better.Considering the 512MB of RAM is the bare minimum requirement and the relatively low bandwidth of 6200 GPU I reckon you better sacrifice every detail of the Advacned settings including turning Off the Shadows which will buy You some frame rates.Also Check for the latest Nvidia drivers and keep em upto date.