I found out how to turn on VSync in PS. Goto opengl.cfg in PlaneShift\\data\\config. Open it and find Video.OpenGL.FpsLimit =, the value is in ms. You have to find out how many frames you want in 1000ms. I wanted to limit my fps to around 30 frames per second. 1000/64=15.625, I use Video.OpenGL.FpsLimit = 64 . It looks like it would stop around 15fps but it gos a bit over to 30fps for some reason.
This helps some of the lag, If your fps jumps up to 100+ then has to slow down to 30- when you look around.