It runs smoothly, though it didn't feel fast due to the unnecessary clicks. It doesn't matter which card you click, there is at most one possible move, so you could just remove the need to click on the empty space, even more so because you cannot deselect a card once you have clicked on it. Only half the clicks needed, whoosh!
Also in a physical variant of this kind of game you can always move several stones/cards/whatever at once when they are in the same column/row which also speed ups the game significantly.
I found the sounds to be a bit unpleasant to the ear if heard repeatedly.