IO-related freeze

My Macbook Pro is misbehaving. Every few minutes, it will freeze for about 10-15 seconds while accessing the hard drive. I recently enabled file vault for my home directory. I have run the disk utility on both the hard drive and the sparse image of my home directory. Not sure what is going on here. I guess I will create a new account that doesn't have file vault and see if it behaves the same way.