Monolith recommend a GPU with 3GB VRAM for just High textures (just textures).
If by "ultra settings" you mean textures as well, yes, you are going to have lag problems in a LOT of places.
Most 760s have 2GB VRAM, so you'd be pushing it just to run high textures. Depending on the speed of the card and other settings though, you may be able to run High textures anyway.
If dropping textures to high still results in some lag, try dropping shadows to high, then ambient occlusion, one at a time to see the results. You can also try turning off Order Independent Transparency.
If you STILL get lag, a last resort is capping the FPS to 30 with the in game frame limiter. If the result of that is unacceptable, I suggest you just play at Medium...