Great tips thanks!  I'll try it as soon as I find my Carrara disk to reinstall it (I just built a new system..)

Quote - I actually am somewhat new to Carrara 7, so after searching the DAZ forums for... well, a while, I compiled a bunch of tips for optimizing render times and memory usage.  They worked quite well for me so I thought I'd share.

I can't take credit for these tips, I'm just sharing what I found.

1. Set the scene up however you plan it to look (obviously ;P)
2. Go to File -> Preferences -> Imaging, Scratch Disk.  You can either A: Uncheck Texture Spooling, or B: Leave it checked, and slide the Memory Usage to 100 MB or less.
3. In the Shader Room, remove any unecessary displacement maps from surfaces by hitting the Displacement Tab and unchecking Enable Displacement.  (Like for distant objects where the displacement might not even show up in the final).
4. Go to Edit -> Remove Unused Masters, then select Remove Objects, Remove Shaders, then Consolidate Shaders.
5. Save the scene and close Carrara (to free up the RAM).
6. Re-open Carrara, but DO NOT open the scene in the Assembly Room, instead go to the Render Room and add the scene to the Batch Queue.
7. If you're using networked computers, start Render Node.  (Highly recommended as it will use the networked computer's available RAM.  Make sure to follow Step 2 on those computers as well.).
8. Set up your rendering preferences as you want them, then it "Launch."
9. Keep an eye on the memory usage in Task Manager if it seems to be lagging.  If the usage starts eating up the RAM, pause the render and close the program.  Reopen it and relaunch the render from the Batch Queue.  (NOTE: I have not tried this step, but apparently if you do this it will pick up from where the render left off without starting the render over.  If something bad happens, please don't kill me.  hides)

This alone cut down my render time, so maybe this will help other C7 users.