"The NVIDIA GeForce GT 750M SLI is a high-end DirectX 11-compatible graphics solution for laptops, consisting of two GeForce GT 750M. Each card has a 28nm GK107 core based on the Kepler architecture. With SLI, each card usually renders a single frame (AFR mode). Therefore, it may suffer from micro stuttering in low fps ranges of 30fps. This happens because of different timespans between two frames (e.g., irregular delays between sequential frames)." (from notebookcheck)
Change from SLI to one GPU. You can change it back when you need to.
You can turn off SLI in the nVidia Control Panel.
This will allow better rendering at lower frame rates and save power.
You can probably set the second GPU for PhysX, see if that helps.
http://www.bing.com/...tedIndex=2