Slow response times

I recently bought the Samsung A900, but the phone's response times are frustratingly slow. When i press the 'menu' key to access the main menu, it takes a long time to respond, between 3-6 seconds. And also, when I quickly scrolling around the icons in the menu page, it seems to pause for a bit and then catches up.. if that makes sense? Is it a fault of the phone, or is it just like that?

Sometimes when you use a lot of the phones internal memory, it likes to get a bit laggy. Have you stored a lot on your phone?