I'm having this link statement:

List<UserGroup> domains = UserRepository.Instance.UserIsAdminOf(currentUser.User_ID);

query = (from doc in _db.Repository<Document>()
         join uug in _db.Repository<User_UserGroup>() on doc.DocumentFrom equals uug.User_ID
         where domains.Contains(uug.UserGroup)
         select doc)
.Union(from doc in _db.Repository<Document>()
       join uug in _db.Repository<User_UserGroup>() on doc.DocumentTo equals uug.User_ID
       where domains.Contains(uug.UserGroup)
       select doc);

Running this statement doesn't cause any problems. But when I want to count the resultset the query suddenly runs quite slow.

totalRecords = query.Count();

The result of this query is :

SELECT COUNT([t5].[DocumentID])
FROM (
    SELECT [t4].[DocumentID], [t4].[DocumentFrom], [t4].[DocumentTo]
    FROM (
        SELECT [t0].[DocumentID], [t0].[DocumentFrom], [t0].[DocumentTo
        FROM [dbo].[Document] AS [t0]
        INNER JOIN [dbo].[User_UserGroup] AS [t1] ON [t0].[DocumentFrom] = [t1].[User_ID]
        WHERE ([t1].[UserGroupID] = 2) OR ([t1].[UserGroupID] = 3) OR ([t1].[UserGroupID] = 6)
        UNION
        SELECT [t2].[DocumentID], [t2].[DocumentFrom], [t2].[DocumentTo]
        FROM [dbo].[Document] AS [t2]
        INNER JOIN [dbo].[User_UserGroup] AS [t3] ON [t2].[DocumentTo] = [t3].[User_ID]
        WHERE ([t3].[UserGroupID] = 2) OR ([t3].[UserGroupID] = 3) OR ([t3].[UserGroupID] = 6)
        ) AS [t4]
    ) AS [t5]

Can anyone help me to improve the speed of the count query?

Thanks in advance!