Path tracing is a computationally expensive method of three dimensional rendering that aims to accurately simulate the propagation of light. A large amount of time is typically spent calculating intersections between rays and the scene, which is composed of triangular meshes stored in some form of bounding volume. This time can be reduced by lowering the overall number of triangles in the scene. Path tracing works by casting rays from the camera into the scene, reflecting until they hit a light source. Secondary rays, or rays which occur after the first intersection, usually contribute less to the overall image, yet require much more time to calculate than primary rays. This thesis found that significant performance gains can be made by using lower level of detail (LOD) triangular meshes for secondary rays. While the lower LOD models are less accurate, they still provide a good approximation of the mesh for secondary rays. Scenes with 1.4 million faces could be rendered up to 10% faster using a 1/32 ratio level of detail for secondary rays. A study with 14 subjects who ranked images based on image quality showed they were unable to differentiate between low LOD and full LOD images
