Why is there latency beyond a single frame at all?? I did a very quick replica of the camera frame counting on Windows with a 144Hz display and it's definitely

Why is there latency beyond a single frame at all?? I did a very quick replica of the camera frame counting on Windows with a 144Hz display and it's definitely below the camera's 60FPS, i.e. the cursor moves on the same frame that the mouse moves. Moving a window also has 0 lag in that test.