I've noticed lately that my 13" MacBook Pro (2009 model) is really lagging in terms of opening applications. It's also freezing a lot, to the point where the rainbow wheel doesn't go away and I have to power off the laptop by holding down the power button (it rarely shuts down from the menu). My internet is also really slow, and I know it's not my ISP because the other devices in my house work fine. Never had this problem with a MacBook before. Any advice on how to fix this issue?