Serval reasons: (1) noise from handle chain being metal-consider switching to lighter plastic type. (2) The rubber flap which lifts up when handle is pushed down and seals "when handle is let go" to allow water to fill in take maybe worn to the point of needing replacement-Go to any Lowe's/HomeDepot and they will walk you through replacement process of just removing old one and putting ends in place over hooks to install new one. Takes me 1 minute to do. (3) Adjust the water cut-off valve that supplies water to tank so it can feel up rapidly by just turning the value. If value is hard to turn try using some oil or WD-40 on it. Remember that one way opens to allow quicker fill up and better flush and other way just turns water to toilet off. If now of these things work then just give me a yell and I can advise further.