I can't either. I gave it a good go locking to 30 fps with 30hz and FFTF=0.1. Even with setting that delivered well over 40 fps with Vsync off and Frame rate set to unlimited I see long frame stutter and the odd burst of micro stutters once I turned Vsync, TB on and limited the Frame rate to 30 or 31. Once I reverted back to Unlimited Frame Rate those stutters completely disappeared. Only I suspect that with Unlimited frames the autogen loads closer the aircraft than it does with limited frames. (I'm not sure about that. Will require further testing). All things considered Prepar3D V5 is awesome. It's a huge improvement over V4. Particularly and almost entirely because of TrueSky. I need 20GB of VRAM please!🤪