See, when you're swooping your attack isn't sent to the server until you stop. When you swoop into someone else you stop, and your attack goes off (assuming you are holding the attack button down), so there is no .9 second delay. When you are standing still melee simply fires every .9 seconds and nothing happens in the meantime. You don't have to worry about attacking at the same time as your opponent unless he happens to be timing his attacks to the tenth of a second with you.