Photoshop :: CS6 Memory Usage 14GB From 50 Meg File?

I'm working on a 48 meg file, but my RAM usage was up to 13.9 gigs. I just restarted Ps and opened the file and it's up to 10.7 gigs.
 
Previously I was always maxing out 10 gigs everyday out of 12 available gigs in the machine also working on small files.( 25-30 meg on average) IT tried playing with things forever and finally just tried ordering more RAM. They ended up putting 28 Gigs in the box. And I'm really not seeing any advantage in Photoshop, other than my system still runs OK outside of Ps while I'm working. well Rhino 3D still crashes from being out of memory, even though there was still 6 gigs free?
 
I'm just drawing, no filters, not too many layer masks. I do have maybe 15-20 vector smart objects in the file, and I'm at 147 layers. The issue I was having is Pen lag on the Cintiq when I draw starts getting horrible as the RAM usage gets higher. I had been restarting Photoshop constantly to get it to release RAM. But I haven't the last couple days since they doubled the RAM in the machine. And obviously on restart the file still needed a lot of RAM???
 
I can live with the lag, sucks, but I can still work. I just don't understand why these small files are using so much RAM. Back in the day on 32 bit systems with 4gigs of RAM I would sometimes create posters/covers/magazine spreads that were 1.5- even 4 gigs that would have to be saved as Tiff's because PS didn't support a file that big. This machine runs like that everyday. At home I've been doing some freelance book covers that get up to 450 megs now and then and it still runs better, Cintiq at home draws smoother than this machine that costs 3-4 times more!
 
It's a win 7 64 bit box, 2 Dual core 2.4 Xeons. two quadro 2000's, now 28GB ram, OS on a 560?GB drive with files on a Terrabyte drive that gets backed up. My hardrives arent rated very high, 5.9, but at least im working local to the machine as the network is slow.