[horde] Slow address book queries

[netty 2006]

Hello,

I'm running:
    * Horde: 3.1.1
    * Imp: H3 (4.1)
    * Turba: H3 (2.1)

(Yes i know i need to upgrade)

Now horde is running too slow. I see below in mysql slow query logs:
=====================================================
# Query_time: 5  Lock_time: 0  Rows_sent: 1  Rows_examined: 84412
SELECT c.datatree_id, c.datatree_name FROM horde_datatree c LEFT JOIN
horde_datatree_attributes a1 ON a1.datatree_id = c.datatree_id WHERE
c.group_uid = 'horde.shares.nag' AND ((a1.attribute_name = 'owner' AND
a1.attribute_value = 'xxxxxxx at xxxxx.com') OR (a1.attribute_name =
'perm_users' AND a1.attribute_key = 'xxxxxxx at xxxxx.com' AND
a1.attribute_value & 2) OR (a1.attribute_name = 'perm_creator' AND
a1.attribute_value & 2) OR (a1.attribute_name = 'perm_default' AND
a1.attribute_value & 2))   GROUP BY c.datatree_id, c.datatree_name,
c.datatree_order ORDER BY c.datatree_order, c.datatree_name,
c.datatree_id;
=====================================================

Any idea how can i speed things up?

Regards,
Netty