In my opinion gaming on 30 FPS is extremely horrible. Especially with shooters. This has in part to do with the 33.3 ms response delay that you can get between moving the mouse and the change being processed and shown on the screen. When compared to the reaction speed of ~200 ms, you add a 15% delay. Compare that to 144fps (6,94ms frametime) you loose only 3,5% which makes the perception much smoother