First note that the primary reason for delaying frame rendering isn’t reducing latency, but rather decreasing the time where the window manager is unresponsive to, for example, a request to map an application window. In general, I’d agree that a couple of frames of latency isn’t a big deal. (If you look closely at the timing diagram above, you’ll see that the maximum latency for event handling is actually 2 frames… I want to get into latency a bit more when I discuss the interaction with applications.) But it’s not completely ignorable: consider drag-and-drop – if the user is moving the mouse at 500 pixels/sec, then a frame of latency is 9 pixels of lag. In any case, it’s important to have the concepts and visualizations to be able to think about the implications of one algorithm or another for latency, which is my main goal in writing this stuff down.

But good that it finally gets done

Also, it looks like you want to move the rendering closer to the swap. Isn’t that a bit overkill, I would think that latency of 1/60 of a second is enough for anybody.