Facebook is not closing your session locations, when you log off. This is causing Facebook to run extremely slow, and games to crash on a consistent basis. In order to fix, you have to manually end activity on your sessions. Once I closed my active sessions my performance improved drastically!!
Look to the upper left and click Security
Active Sessions - click edit
Once you are on the security page, it will tell you how many sessions you have open. End all but your current session.