A friend of mine whom which I play Neverwinter Nights with on server has a Vista OS and constantly experiance performance issues (lagg for short) so after browsing the web for about a hour and going by suggestions and feebacks I managed to solve his problem as how now plays without even the hint of lagg. I would suggest trying "Step Three" before the others.
Step One: (Nivida Graphics Card With Control Panel Only)Spoiler: show
Step Two:Spoiler: show
Step Three: (Try This Option Before The Others)Spoiler: show
Some Nvidia's 400 and 500 series graphics cards had stuttering issues with NWN that a recent driver update fixed. It is possible that while the computer is new the drivers that come pre-installed on it aren't actually particularly recent and as such don't contain that fix. You could try updating the graphics driver.
Is it just NWN? NWN utilizes an old OpenGL shader that the 400 and 500 series nvidia card hardware no longer supports. Without it, anything that utilizes transparency (cloaks, robes, bows, list goes on) in NWN will annihilate your framerate. The last few nvidia driver releases add this support via software so it isn't a problem anymore, but if you have the old drivers, you still have the old problem.Awesome! NWN has long been running so piss poor for me that doing anything beyond socializing in game has been a nightmare, and even then FPS has been uneven enough that I can't properly see what I'd been typing in anything better than a couple of second intervals. Given the issues I suffered, I just kind of stopped playing the game and amused myself with other things. I updated my GPU drivers a few days ago in an effort to defeat a frequently recurring black-screen in Dead Island (The new drivers fixed that too), so I was already sitting on the latest drivers, but I hadn't bothered testing them in NWN. Then I come to see your post here, and figure, "Hey, maybe I'll go see if there's been any improvement." Testing the game, I actually get performance that's just as good as it always used to be on my old computer. Many thanks for that comment, without it I would probably never have gotten back to NWN at all. :)