Can't play ghosts because of lag.. Got good pc

Hey! im experiencing a lot of lag in ghosts. I can't even move because of the lag. It's in multi and singleplayer.. For example in singleplayer " first mission lag free" second mission exactly when i get  a weaopon i freeze out. And that's the same on multiplayer.. i freeze/lag when im going to choose a team!

PC Specs: Intel Core i5 2500k-@3.3GHz
                 GTX  760 Windforce 2gb GIGABYTE
                 Xilence 650 W

                 Corsair Vengeance 8gb DDR3

                 Windows 7 64Bit

                 Samsung monitor 60Hz

                 MSI motherboard Z68A-GD55

Please Help!