The GeForce Forums have a statement from NVIDIA about how they are working "as quickly as possible" to address performance and stability issues being reported when playing the new Tomb Raider game on their hardware (thanks HARDOCP). Here's word:

We are aware of major performance and stability issues with GeForce GPUs running Tomb Raider with maximum settings. Unfortunately, NVIDIA didn’t receive final code until this past weekend which substantially decreased stability, image quality and performance over a build we were previously provided. We are working closely with Crystal Dynamics to address and resolve all game issues as quickly as possible.

In the meantime, we would like to apologize to GeForce users that are not able to have a great experience playing Tomb Raider, as they have come to expect with all of their favorite PC games.