Sounds more and more like a DesktopHeap problem. Chrome opens quite a lot processes in the background, even when there is only a few sites/tabs open.
DesktopHeap is a tricky beast, and works on a very low level in Windows.
To my knowledge Windows 7 (x64) reserves 20MByte of RAM (per Windows account) to open windows in Windows. And once you hit that limit, no matter how much RAM you have in your PC, no program will open anymore and your computer becomes very (and I mean very!) slow.
At some point in time I tried out how much instances of Excel I could run simultaneously using Windows services on Windows XP. After maxing out the DesktopHeap values for that OS I maxed out at 8 and it took almost an hour to kill each Excel instance. It is frightening how much resources and handles Excel consumes when compared with other Windows applications or even with the other Office applications.
Take a look at this KB article
from Microsoft if you want to know more about this.
For Windows XP/2003 (32-bit) Microsoft had a very rudimentary tool available. After a convoluted installation procedure it would show you where "all" that RAM went. XP has only 3MByte of DesktopHeap.
For 64-bit PC's you have to trust a blogger who adjusted the MS software so it works. You will find that link soon enough with Google, I purposely don't link to it.
Oh, before I forget, if you have a multi-core processor you will need to download and install Windows Symbols for Debugging (only 330MByte) to enable the DesktopHeap software to install an unsigned driver that it needs/uses to show you these values.
Which means that you have to reboot your PC and disable the signed driver check when the system is booting.
Anywayz, when you have successfully gone through all the hoops, this software does help in finding resource hogs, which does make it worthwhile.
Seriously, only do the above if you are up for it and really want to know, else don't even start.