Triple buffering maintains a queue* of fully rendered frames ready to be displayed by the monitor. What I'm talking about is a queue of rendering commands for frames that still need to be rendered by the GPU.
* triple buffering does not actually use a queue, but rather two buffer swaps, which means a frame is allowed to skip ahead if completed early.
Turning it off means doing what instead? No vsync at all will certainly give you faster updates, if you don't mind the tearing. But in general I would describe triple buffering as a way to reduce lag when vsync is on but your system is fast.
