Try to use this settings in nvidia control panel:
Ambient oclusion :Off
Antisotropic: Aplication Controled
Antialising: Aplication Controled
Antialising Transparency: Aplication Controled
Cuda: All
Maximum pré Rendered Frames: 5
multi Display: Single
power Management: Maximum Performance
texture filtering: Off
Negative LOD: Allow
texture Filtering: Quality
texture Trilinear: ON
Threaded optimization: Auto
triple buffering: On
vertical Sync: Aplication Controled
For me work very good, and have high FPS rate
