My iCal is running slow and is empty.

I have my gmail linked to my iPhone and my Mac. However, lately it has been running slow and shows that I have no events at all, not even in the past years. My iPhone, however, shows that there are events. It shows that it the account is on there (The check box is checked). My iCal takes too long to remove the gmail account for me to reset it and freezes; I have for Force Quit it then. How do I fix this problem? Thank you in advance.