Just trying to get Mavericks server working, and logged in as an Active Directory user on it. Seems mds_stores is using a large amount of processing. found this post which says to turn it off, in terminal type:
sudo mdutil -a -i off
This is the message in terminal I got when I typed the command in:
/:
Indexing disabled.
/Volumes/Scratch 1:
Indexing disabled.
/Volumes/Scratch 1/Home Folders:
Indexing disabled.
Might be to do with the fact I was trying to get home folders working, something to do with profile manager. Anyway, the command did stop the large processing.