When you render your scene using BSP2 the rendering takes a long time to complete
You have a complex scene that renders very slowly when you use BSP2.
There can be slowdowns when rendering complex scenes (e.g. scene that involve millions of polygons) when you use mental ray and BSP2. This is issue is due to a problem with the scene translation. In 3ds Max, there is a setting used for displacement called view-dependant approximation that is turned on by default, even when there is no displacement present in the scene. This can cause a slowdown when rendering with BSP2 due to the time necessary to perform this translation.
If your scene does not use displacement, then you can work around this issue by disabling the View-Dependant Approximation before rendering.
To do so:
Open Render Setup (Rendering > Render Setup or F10)
Go to the Renderer Tab
Under the Shadows & Displacement rollout, in the Displacement (Global Settings) group, uncheck "View"
After making this change, the time required to render the scene will decrease substantially.
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