iCal Cleaner... Over time, iCal can become filled with all kinds of bogus data like duplicate events, blank events, duplicate alarms and more. All of this extra baggage adds up and can make iCal sluggish.
iCal Cleaner is a free utility designed to clean up common problems in iCal. Just launch iCal Cleaner, select the calendars you want to clean and the action you want to perform, and click Start. Then sit back and let iCal Cleaner do the rest.