After Effects :: 3D Shape Taking Forever To Render?

I have simple composition that animates a two shapes that I am using as a "screen" to show photos.  The shapes are 3D; the camera movement is minimal.  I have an Ambient light and two Spot lights. 
 
I am on a one year old i7 processor with 16 GB of RAM.  Cache files are written to an SSD. 
 
Still it is taking a long time to render (it's a three minute project and takes about 20+ hours to render), and there's no pics added - just the "screen".
 
The final project is similar to the many templates you can find that show photos/videos.   It's basically a fancy slideshow, but unlike those you can buy, it will hold 25 to 30 pics. 
 
Any thoughts on what I can do to either use something other than a 3D shape (but still keep it 3D) or change parameters or workflow to cut down the render time. . .  I am pre-rendering the composition now (which will take the 20+ hours) but obviously, if I want to change anything with the movement or the overall length, it means another day of rendering.