Putting that error (without the datetime) into google and following the first link and the response it gets leads to reading the audispd and audispd.conf man pages, the latter contains this useful information
q_depth This is a numeric value that tells how big to make the internal queue of the audit event dis- patcher. A bigger queue lets it handle a flood of events better, but could hold events that are not processed when the daemon is terminated. If you get messages in syslog about events getting dropped, increase this value. The default value is 80.
So read the manpages, and increase the queue depth.