http://en.cdprojektred.com/support/tw3-system-requirements/
They say that 6GB is
required as well as
recommended. According to this, your 8GB should be more than sufficient. Sure, more RAM is always helpful as disk cache, but you are talking about constant stuttering, aren't you. Do you have mods installed -- that's the rightfully standard question I would have expected from Hickory (greetings, mate, you've been most helpful), like, texture mods that might fill up your Video RAM?
My first guess, though, would be an anti-virus tool running in the background. (You'd be surprised how well MS Office runs w/o an AV -- even better than LibreOffice under Linux. ^^)
So: Disconnect from the net, disable the AV, reboot, and check again ... if you haven't done so at this point.
And check the Task Manager about what might eat up your CPU cycles and/or block the file systems. (To me, a real show stopper for anything under Windows is the file indexing mechanism -- it's the first thing I disable)
My second guess is, that, well, your CPU seems to be near the lower end of the spectrum. I have no experience with that, I'm afraid (ahem, with this game and this my rig ^^).
In my limited experience, tweaking by means of the Nvidia control panel or the tool provided by the 3d gurus works only if you know what exactly you are loooking for.
Just guessworks. :/
