When you have a polygon intensive scene in Maya, you may want to consider optimizing the render by using proxies for rendering.
Learn how to Render very large poly count scenes in Mental Ray using proxies
This can be done in a lot of rendering engines, such as V-Ray, Arnold, and even in Mental Ray using Mental Ray Proxies.
Being able to load objects on demand in the renderer can prove to be a much more efficient workflow that will allow you to use your system resources more effectively.
Daryl shows how to set up mental ray proxies and presents some great workflow tips for working with them.
