Oh Ya, Bump maps, they will kill your render real fast. I do all the above. I render in layers, I resize all my textures, don't use bump maps if I can get away with it. I use low rez figures when I can. I render 2X's the finished image, better for postwork. I save eveything as a tiff. Don't make me count how many layers I do, there are more than I have fingers and toes. You can render all your figures without clothes and props to get the proper shadows, then render each figure with clothes. There are so many work arounds.