Check out the Captain Sim 767-300 review on Flightsim.com.

In there the reviewer suggested this for NVIDIA users:

"Go to your control panel->Additional options->NVIDIA control panel->go to manage 3d settings->Under 3D app visual simulation scroll down to the bottom and look for Vertical sync->move to the right and hit "Force off" This improved performance in the cabin vastly for me. There still was a bit of lag but nothing as compared to before."


I run ATI so I can't vouch for it.  Worth a try.