No unfortunately. The only memory management you have is the render segment limit which will simply devote more RAM to the render buffers (can help to speed up rendering time is all).
With the problems you describe, I'd say there's a couple of options open to you:
(1) Set your bounding box threshold lower. This way, if large objects are causing LW to lag when you manipulate them, then this will cause LW to simply draw the object as it's bounding box when you manipulate it - speeding up the screen redraw and therefore responsiveness.
(2) Replace your object with a low-res proxy. Essentially, create a lower resolution stand in model that has the same general dimensions as your hi-res one, then use the layout 'Replace' button to swap the object out. Remember to swap it back in though after you're done
