No. If the game renders on time, what you see on screen is always the latest completed image that was ready at previous vsync. With two buffers, if you render

No. If the game renders on time, what you see on screen is always the latest completed image that was ready at previous vsync. With two buffers, if you render too long and miss vsync and then call flip() which waits until the next vsync, you're wasting the frame waiting (because the system can only swap buffers at vsync, to prevent tearing). The third buffer only exists so that the game can start working on the next frame, while two of the buffers are "locked" (one on screen, other ready for display, third available).