Game freezing / Crazy lag?

[JFKH]

I have recently been experiencing very long periods of lag or my game just freezes while I am doing something. I don't think I have changed anything with my comp, and my friends say that it isn't the server because they are on now and they are fine. Any tips for me what may be causing this problem? My internet is fine I can use any browser w/o lag ex: explorer or firefox.