Fullscreen VS Windowmode Performance?

Normally i am a FSX windowedmode user but when flying VFR i have tried with fullscreen.

But i seem to have way lower FPS using 1/2 refreshrate in NI. This is with drivers 335.23.

I dont recall having this with the older drivers but again i am not so experienced in fullscreen.

Anyone who can confirm the loss of FPS (but still smooth) I think Vsync is cutting in half

Michael