I don't know what you mean by "multiple passes". 

When you hide/make invisible a figure or prop, Poser doesn't have to process the item during the render, so less memory is involved and rendering is quite often faster.

My computer is old and only has 384 MB of RAM so I have to hide parts of whatever I'm rendering and reassemble it in Paint Shop Pro. I save as a .png file so that there is no background.  Your image for example would take me at least 6 renders to do, maybe 12 because depending on the texture sizes, I sometimes have to render a figure by top half and then bottom half.  I sure miss my laptop :(

"It is good to see ourselves as others see us. Try as we may, we are never
able to know ourselves fully as we are, especially the evil side of us.
This we can do only if we are not angry with our critics but will take in good
heart whatever they might have to say." - Ghandi