Because your prior RAM usage did not exceed 4GB, the upgrade from 6GB to 12GB did nothing for you.
Pro/E won't use more RAM just because more exists.
That might be true fro some applications, but not Pro/E.
As to the pagefile size:My general rule is that it should be zero to 1X of RAM (on 64-bit systems with more than 4GB RAM).
If you find yourself needing more, you really should get more RAM first.
In your case, you could disable paging altogether since you are nowhere near using 12GB.
Walled Lake, MI
In Reply to Dave Clark:
I've recently had a RAM upgrade from 6GB to 12GB on Windows 7 Enterprise, and I'm not seeing a difference in Creo's performance. I've made the pagefile size 36GB, as I had read somewhere that it should be 3X the RAM size. I'm never seeing the RAM usage go much over 4GB. I would think the models I'm working on would definitely take advantage, but I'm not seeing it.