Trim auditData table
If the audittable grows to fast, you can use the Trimauditlog features of STSADM to delete audit entries older than a certain date.
For example (To specify a date of July 4, 2008, and the content database name WSSContent123456, you would use the following syntax:):
stsadm -o trimauditlog –date 20080704 –databasename WSSContent123456