skiplist vs db format

[throwaway-it at cox.net]

For those of you who have converted from the Berkeley db to skiplist, what kind of a performance improvement did you receive?

We are using Berk. db4 and the IO wait for the disk containing the db is consistantly over 50%.  The partition is 7GB, which also contains the user, quota, proc, and db directory.  It resides on an STK V960 fibre channel, RAID 1 disks.  I am seeing "DBERROR db4: nnnn lockers" errors with the number over 10,000+ ... usually soon afterwards, the imap process needs to be restarted. 

Also, the 'imapd -s' and 'pop3d -s' process unexpectedly dies and SSL connections are no longer possible until imap process is restarted.  Is this a known problem?

Our platform is :   
Cyrus 2.1.11
Solaris 8, Sunfire 280R
4GB memory, 2 CPU

Thanks,

  Bob