Hi. I am experiencing a weirdest ghx issue ever.
I tuned all to Ultra to see how it looks, but my CPU is not strong enough so I disabled Vsync, Ubersampling and Anti-alasing. I also set textures to Medium. LOD distance is at Normal.

And it behaves now WAY better than on medium or high! :O
But here comes the weirdest part. It runs so smoothly only in battles and in gameplay. For some strange reason most of the dialogues and cut-scenes now are at very low FPS. I exit dialogue and the FPS rises up again... Why? What setting do I need to change?
I've got:
AMD Phenom X3 2.4Ghz
ASUS ENGTX 460 OC, 768MB
8GB or RAM
Windows 7 x64
Also a sudden plunge on a sullen swell. Ten fathoms deep... on a road to hell.
And Witcher's amulet (the most important, I haven't have a single crash and I have completed the game once already).

UPDATE:
Seems like if I press esc twice or alt-tab out and back into the game while being in the conversation the lag disappears... What is this??? My CPU load spikes when I enter the conversation, but once I press ESC or atl-tab back in it goes to normal again and log lag occurs anymore... Furthermore: it seems when I change any graphics settings, it doesn't seem to help. And I didn't have that during my first playthough...

And one more request if CD Project reads this: would it be possible if you would make real Witcher's amulets? I mean the head is awesome and all, but my dog didn't care much and broke it on the second day...

Anyone???
Well since you all have been so kind to help me, I have figured it out myself. Turned Everything to High instead of Ultra then "reloaded resolution (changed it started the game, quit, changed back to 1920x1080 and started the game again). No lag anymore, and the game runs as smooth as it did on Ultra in gameplay too. But on Medium and Low it still runs worse :O