It could be some kind of placebo effect, but I know the difference between 60 and 150+ fps even on 60hz screens. At least I'm sure I can feel it when gaming.
It is 100% placebo because a 60 hz screen can only render 60 fps. If you're getting 150 fps, then if you're playing with V-Sync enabled, only 2 of every 5 frames is being shown to you. The other three are being thrown out, never reaching the monitor. If V-sync is disabled, then you're only seeing about 2/5ths of every frame with a tear in the screen when the next frame was shown, causing rendered objects to shear.
