I'm guessing the project is in 24/96K?
Try doing it in standard 16/44.1.
If that helps, try one at 24/48
projects will get titanic In size fast at higher bit rates..
It eventually has to bounce to 16/44.1 anyway to burn to cd.

I run at 24/48k and have NEVER run into performance issues on either a system with an i7 2600k OR a system with an AMD A10 7850 (Both with 32 GB of memory).
 
I also have one SSD for Windows (Win 10) and all applications, and multiple 7,200 RPM HDD's splitting Cakewalk Projects, Native Instruments and Miscellaneous samples, and EastWest samples.
 
I run with CPU min/max both set to 100% and my cores are not parked.
 
Bob Bone