Problems with expire

[Paul Mindeman]

The system:
Redhat 6.2
INN 2.3 using CNFS for storage and traditional indexes
70 GB of space in a RAID-5 configuration

For around the first week, everything was running reasonable smoothly.  
Expireover and expire took about an hour to run each.  Starting on 
Friday, expire has taken longer to run, taking 3 hours on friday, and 
more than 30 hours on Saturday and through Sunday.  Expireover still 
only takes an hour to run.  The history file is only twice as big as it 
was a week ago, at 600MB.  The expire.ctl file is set to /remember/:10.

Any ideas on why expire is taking so much longer to run?  Are there any 
adjustments I can make to the server so that expire takes a more 
reasonable amount of time to run?

Thanks,
Paul