I recently upgrade my graphic card from 560 Ti to 780, and expecting a really smooth game.
Well it is, until I got to Revenant's Toll and point my camera to the crystal, the frame rate just drop below 20 fps.

I'm running Windows 7 64 bit, have the latest driver installed, my other hardware are not top class but still quite decent: CPU i7 930, 12 GB Memory.

The game graphic setting is set to maximum, is this normal or something wrong with my computer?

Thanks.