Is it possible to improve on the rendering speed of an animation by exploting the fact that the scene doesn't change much between frames? Is blender recalculating everything from scratch for each frame? In my scenes I usually have a small object moving while the rest of the scene is pretty much static. The character will definitely change the ray paths, so it will affect the scene, however I think most of what was computed for the previous frame should be reusable. Is it achievable?