[1] A videogame console or PC will send out a new frame once it has finished performing the necessary calculations to create it.
Using common a 60 Hz monitor as an example, the maximum theoretical frame rate is 60 FPS (frames per second), which means the minimum theoretical input lag for the overall system is approximately 16.67 ms (1 frame/60 FPS).
Individual frames need not be finished within the interval of a screen refresh to output at an equivalent rate.
Game engines often make use of pipelined architectures to process multiple frames concurrently, allowing for a more efficient use of the underlying hardware.
In addition to the latency imposed by the screen's pixel response time, any image processing (such as upscaling, motion smoothing, or edge smoothing) takes time and therefore adds more input lag.