Havent read the whole thread so dont know if this has been suggested yet but I also have a GTX 680 with a good amount of ram and an i7 processor...and SWTOR ran like absolute crap and often had serious performance drops.
This will until I installed SWTOR Unleashed....night and day difference.
So yeah get SWTOR Unleashed and see how that goes for you!
Here's the link to SWTOR Unleashed thread:
http://www.swtor.com/community/showthread.php?t=529567