Comparing Indexing Speed + ZFS question

Hi, have two quick questions: I am re-indexing some large mailboxes and I wanted to get some opinions on these speeds. I ran a random sort command on an unindexed mailbox in order to get it to index. Results, for a mailbox with 10GB Inbox, spread in 65 000 files: 3 UID SORT (ARRIVAL) US-ASCII OR OR OR FROM "dfgfgfgf" SUBJECT "dfgfgfgf" TO "dfgfgfgf" CC "dfgfgfgf" a03 select INBOX

• SORT 3 OK Sort completed (2455.549 + 0.122 + 1.477 secs). Index cache file at the end was 31MB in size: 30756376 Apr 18 02:14 dovecot.index.cache Is that normal, slow or fast ? Second question is, how can I speed this up ? I store messages using Director over NFS , on top of ZFS. From what I've read it would be fairly safe to disable mail_fsync but I don't think that would help much with the indexing speed. Any other tips ?