on a current project I noticed the following:
Rendertime increases hugely when rendering an object with intersecting geometry and the intersecting geo's visibility turned off via tag. Let me explain further:
Object A is intersecting with Object B (both rather lowpoly but with displacement). Rendering all together takes about a minute, no problems at all. Rendering Object B as a renderlayer works as expected as well, short rendertimes.
Turning off the camera visibility of Object A makes the scene not renderable (about 2 samples per minute...).
Is this a known beahviour?
Due to NDA I can't share the scene