My Nikon D40 is running very slow?

When I turn it on, it takes about 30 seconds to load the home screen.
Also, sometimes after I take a photo it takes a long time to load it.
This has just started recently. Normally it takes no time at all to load either of those things.
Is it the battery?
Is it something that can be repaired?

Try the basics first. Format the card in camera (you will lose everything on the card). Fully charge a battery and reset it to factory defaults.