Brazil Volumetric Environment

I’m rendering a scene using a Brazil Volumetric Environment. I have only one light (spotlight) plus I’ve turned on skylight and indirect illumination. Scene is interior of a tunnel with a hole in the wall to let the light in. The render is taking ages to start. After nearly 30 mins it doesn’t have a single pixel rendered yet, at 800x600. I did render at a much smaller size a while ago and it did get started after about 4 or 5 minutes, but I’m wondering if some setting is creating issues or is this type of environment always slow to start.

Using i7 (quad core), 24GB RAM, Quadro3000M.

It will certainly add time to the render, but it should be nothing like that. Could you either post the model here, or send it to me at - and I will figure out what’s causing the slowdown.