Something prolonged is long and drawn-out — it's taking longer than it should. A prolonged wait is usually annoying.
If a fan throws a drink on the court during a basketball game and it takes an hour to clean it up, and then another hour to re-wax the floor, and then another hour for the players to warm up again...that's a prolonged delay. Anything prolonged has been stretched out further than it should be. America's war with Vietnam was prolonged much longer than anyone expected. If something is tedious, time-consuming, and feels like it's taking forever, it's prolonged.