Memory Of My Laptop

I think upgrading the memory of my laptop could make the performance good. A friend of mine had just do that. She bought laptop memory and since then, her laptop works fine. Before, she said she hate it everytime she downloaded something because it takes too many hours to get it done even her connection is fine. I really don't know what she meant. I am not really an expert of computer thing. If ever i would buy me a laptop memory too, does it help?