So I noticed that my MBP's internet connection was really slow for past few days. But I didn't think nothing of it. Then today it was at the point where I couldn't even open a webpage without waiting for few minutes. I decided to check my airport utility to see what's up. When I checked the MAC address of connected user, I noticed one MAC address that I didn't recognize. At this point I changed the password and tweaked the access control so that only the MAC address of my MBP, PS3, and iPhone can access my network. When I restarted the Airport, everything was fine. Internet connection was super fast. Conclusion? Someone was downloading big files using my network causing the slow down. My advice to all, check your network and change the password at least. It is new year after all, and it is good time to fine tune your network.