I don't know what exactly "display as box" in 3d max do, but i suppose it makes complex scenes faster in modeling viewport, because it makes models more simple? I think Nurbs equivalence would be mesh settings in tools/options/mesh: jagged & faster. It will speed up the viewport model manipulation, but it may give you few graphic glitches, jagged edges and similar; carefully this also affects rendering mesh quality, so be sure to turn it to smooth & slower before rendering.
Also try to use layer options, you can separate geometry on different layers so you can turn off temporary some it will speed up the viewport drastically. Also use "block" command (sometihng like replicator in Modo), to make instances of the same objects that are repetitious - it will free up memory.