V-Synch is good if your monitor flickers at some resolutions. It will improve the rendering of frames on your screen, but it reduces also the fps. If you don't notice no flickering, esp during fast turns, there is no need to activate it.
my fps increased by 200 fps
I tested it offline so I had more than 450 FPS.
I'm about to prove that legoland /picmip doesn't increase the fps on my machine by a value of more than 10. Just testing all resolutions and combinations and posting the result here. I think you modified the ini first to legoland settings and than switched to higher details in the ingame options, what is completely not comparable... 200fps, we will see.