FF Not Using All CPU Cores For rendering (4 Pro Version)

Hi,

I recently downloaded the Beta Pro version 4.0, but FF doesn't seem to utilize all my cores for rendering; CPU usage is only at about 8% in Activity Monitor when rendering and CPU usage is only at about 8%.

In fact when I go to rendering options and select "Use a single CPU/Core" the render times are identical "Use All Available Cores". This leads me to believe that FF isn't using all cores.

FF 4 works fine on my Quad Core windows machine, but I'd really like to get working on my Mac.

I'm using ML 10.8.2, on an Octo-core machine, 32GB ram.

Thanks in advance!