I meant to link that post here a while back... The workaround is for a problem specific to the GTX 4xx and 5xx series. I don't know the exact source of the problem, but after reading that disabling extensions helped, I narrowed down the cause to the two I mentioned in that post. I was getting less than 15 fps much of the time on a GTX 570, but this has brought me up to the playable range. The game is still slow in some areas, but I can't say whether it was any better prior to installing the new graphics card.
You can verify that you have this problem with Fraps by going into an area with no NPCs, removing any ranged weapons, robes or cloaks from your character and then replacing these items one by one. Without the workaround, you'll see a large FPS hit as soon as you equip one of the problem items.
Just want to let you nVidia folks know you're not alone in this. I had this same issue with an ATI card a while back. It happened from a driver update.
As another alternative to using a wrapper you could try reverting to an older driver version, perhaps even the CD of factory drivers that came with the card. This helped in my scenario until a NEW driver version was released, fixing the issue.
Hope that helps.
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Unfortunately new nVidia cards and NWN still have issues. I tried running NWN on GeForce GT 555M and I was getting really low FPS with more than 3 characters on the screen.
I tried applying fixed found in this thread and some other 'solutions' found on the Internet, but unluckily none of them really worked. I think that some of them helped with the FPS in town or docks, when I'm the only character on the screen (10->60), but still when I'm trying to run with couple of people it goes down to 10-.
I really hope new drivers would helped, but apparently nVidia and OpenGL do not like each other. No more NWN for me, unless I change gfx... pft...