Don't bother trying to reduce the polygons.  No one has a slower computer then me.  It's been my experience that by working in orderly fashion this is doesn't have to be problem.  First work  in pieces, don't have anymore elements on screen then is needed to pose and position.  Work in nontexture shaded modes whenever possible.  Save the elements of the scene as sub scenes, Pose presets, and even shader presets.  When you feel you have all the elements finished,  close Studio, wait for the OS to reclaim the memory, restart Studio and put things together and render.