Input events slow on unity Update function

Question

I have this running on the Update() on Unity. I am trying to create a page swipe feature on my game, but the problem is there is a half second delay when printing "dragging" to "end drag" when I release the mouse.

Does anyone have a method that will register input events faster?

void Update()
{
    if(isDragOn)
    {           
        if(Input.GetMouseButton(0))
        {
            print ("dragging");
            //moveContainers((Input.mousePosition.x - mouseLastPosition) * 0.01f);
            mouseLastPosition = Input.mousePosition.x;
        }
        else if(Input.GetMouseButtonUp(0))
        {
            print ("end drag");
            isDragMoved = false;
            isDragOn = false;
            endDrag();
        }
        else if(Input.touchCount > 0)
        {
            if(Input.GetTouch(0).phase == TouchPhase.Moved)
            {
                //moveContainers(Input.GetTouch(0).deltaPosition.x);
            }
            else if(Input.GetTouch(0).phase == TouchPhase.Ended)
            {
                isDragMoved = false;
                isDragOn = false;
                endDrag();
            }
        }
    }
}

Answer 1

There isn't going to be something "faster" than Update(reference), that runs once per frame:

Update is called every frame, if the MonoBehaviour is enabled.

If your frame rate is half a second per frame, then you'll get a half second delay. You'll need to perform some optimizations if you want faster response. Make sure your MonoBehaviour is enabled, and you're not running Update as part of a Coroutine. You can try creating a new project, and just putting your code into a new script on an otherwise empty object.

Answer 2

The mouse input can be theoretically speed up by using a callback-based input API. Because polling-based input API is going to be delayed from the actual input no matter what. Depending on the timing of the hardware, imagine at this moment the Update just passed but you are not yet at the rendering routine. If you were using callback-based input you would have 1 frame advantage and able to update the graphic in time. Unity have keep this callback data for the next frame.

Unity's New Input System is callback-based. But currently (9/9/2018) as far as I tried the callback does not occur at an arbitrary time but queued up and batched together and present the callback to you in the loop, before all Update(). There might be a way to ask the "queued up" data in the future when the API is being finalized, so I think it worths looking out for.

Because I see some touch code I am assuming you might also want the solution to work with touch input. If you use Native Touch you can receive the native touch callbacks as soon as the touch happen, which could be faster than waiting for Update. If you want the same input workflow as native app developement you might want to check it out.