I recently noticed that when I press the piano keys, I do not lift my fingers fast enough off the keys. This causes a "dragging sound". However, I seem to keep the music tempo going. This slow lifting of my fingers, makes the notes sound dragged out. For example, when I played "Danny Boy" it sounded like each note was in slow motion. Help!
I suspect you're holding your hand too low and playing with flat fingers. Raise it, curve the fingers. You shouldn't need to think of consciously lifting your fingers, more of the normal finger position being poised above the key, ready to strike down when it's time to play a note. Can't really help more without seeing you play. You could post a video?
If the keyboard itself is high in comparison to your seated position, it will make your wrists so low, that lifting fingers isn't easy. Your hands/wrists need to be above the board, so sit with your elbows slightly higher than that.
Then, you can use your fingers better, sometimes your whole hand, even, sometimes your whole arms from the shoulder. But, obviously, for faster note articulation, the smaller parts of your anatomy - fingers - are above the keys, not climbing up to press them down. Meaning they need to climb back up to release.
Grand pianos will have a better (faster) release of their own, compared to studio pianos, and electronic ones vary considerably - we don't know what you're using.