

As i have seen in many tutorials on the subject, rendeering passes should take no longer than rendering without passes, as mental ray already calculates these things when it renders the master beauty.
I am currently using maya 2012.
the issue i am having, is that when i attach multiple passes to the master layer (or any other layer for that matter) my render time jumps to anywhere as much as 5 x the original master layer.
Even adding one simple beauty pass to the master layer increases the render time by 30 seconds.
I have searched the internet for answers, but no one seems to have come across this issue.
I understand that the pass system should not add any time to renders, as this would not make rendering passes a plausibe option.
Can someone please help me! Aaaargggghhh i can't take it any longer.

cheers

Adam
P.S.
At first i thought it was an issue due to my scene. The scene has a lot of reflective and refractive materials in it, and a realflow bin mesh.
However, after testing a couple of other scenes, I discovered that the issue still persisted even if the scene had no reflective or refractive materials. Or a realflow mesh.