I am working on a project with a snow / ice surface layer on which I connected the Reflective Shader.  The render was still not complete after over 17 hours.  I paused it, and started over with the same .tgd, but plugged the Default shader and added Specular highlights, expecting to have no effect on render time.  In less than 2 hours, the render was complete.  So the results seem to be the same between the two, but render times (and I've seen it before) with Reflective is vastly longer.  Is this a known issue?  Or does Reflective produce a quality that requires a long render?