Low FPS problem

[SilverSword]

Today I start NWN like any other day, load EfU and notice only one change- unplayably low FPS outdoors. Interiors are 20-30. Which is really perfectly playable, but once I get somewhere like the square, I just drop down to 6-9 (4 when in combat) which is completely impossible to work with. Now I've tried:
1) Updating my drivers to the latest version
2) Going back on a previous version of drivers
3) Tried setting the game to work with the second CPU

Every other game works fine, even the newest of them. Other servers and/or modules seem to work the same way (exteriors lag, interiors ok) and I just can't find a way to fix this. I've to admit those issues happened to me a few times before but I managed to fix them by updating drivers, reinstalling drivers or some other simple stuff. But this piece of problem I just can't get rid off.
My video card is ATI RADEON HD 4870.

Does anyone know any possible solution for the sudden low FPS or has any suggestion? I am getting really desperate.

[Dead Man's Chest]

Try using windows on a lower setting like XP.

[SilverSword]

I got Windows XP.

[Caster13]

Did you have any of the texture packs installed before?

Try downloading Mort's texture pack from here.

[TheImpossibleDream]

I had this issue for a very long time with a different card, it took a very very long time for nvidia to fix it on their end and even the fix is somewhat sub par. Sadly I also stumbled upon a number of people with similar complaints with ati cards. I'm not 100% sure you'll find a fix at all.

You might try turning off "Threaded Optimization" for NWN via your video card settings. I'm not certain how to do that for your specific card though.

Oh and as for other modules working fine, this is an issue ~generally~ occurs when items from the 1.69 patch are visible(such as cloaks or bowstrings). Oh also turn off shiny water if you haven't already.

[Porkolt]

Don't forget the dual core affinity thing. It's a pretty common problem, just tossing this in here in case you don't know what I'm talking about.

[Diz-e]

I had a similar problem with my HD 5570 out of the box. When I updated the driver package, it was resolved. I'm using Win7 Ultimate, currently at Catalyst 11.7 (the problem was in the 10s somewhere).
It could be a DirectX issue too - WinXP only goes to DX9 so not sure what that has to do with the Catalyst driver versions.

I'm really an Nvidia guy and this is my first ATI card, so sorry I can't be more help than that. I can confirm that you don't want Shiny Water turned on! Also I've found that some ATI cards running NWN don't like Environmental Shadows on Creatures.