Why on (press) response so slow on loaded picture?

hello, friends. I have a flashpage which has a movieclip (instance name is gallery) which receives the loaded image from a folder

_root.gallery.loadMovie("…/uploadedimage/"+galleryimageR);

Then I have a set of buttons to control the moving of it up, down, left, right and enlarge or shrink it . I make it in the way that when the user click the gallery movieclip , then press the relative button for moving.

So I have on the gallery movieclip action like
on (press) {
_root.spress=3;
}

and on the buttons for moving, there are action like
on (release) {

if(_root.spress==3) {
	_root.gallery._y -= 5;
			
	}

}

But seems I have to press many times before I get it moving . The response time is so slow. Does any one know why is it? And is there any other way to deal with it? Thanks very much in advance!