The join part uses OR that's why running long I'm trying to make it faster The join part uses OR that's why running  long I'm trying to make it faster 

SELECT sc.clientid
            ,sc.dictionid
            ,sc.firstname 
            ,sc.lastname
            ,sc.DB
            ,sc.DOLS
            ,sc.dlnum
            ,Cons.Description AS ConS
            ,Conc.Description AS ConC
            ,'False' as Assigned
        FROM    [monitor].[uxref] xref 
            INNER JOIN [Monitor].[dbo].[seacc] sc
                    ON ( 
                            xref.regid = sc.[consid] 
                            OR xref.regid = sc.[concid] 
                        ) 
            LEFT JOIN [Monitor].[dbo].Reg Cons ON Cons.RegID = sc.ConsId
            LEFT JOIN [Monitor].[dbo].Reg Conc ON Conc.RegID = sc.ConcId
        WHERE xref.UserId =1000
You may want to try a union of:

 SELECT sc.clientid
        ,sc.dictionid
        ,sc.firstname 
        ,sc.lastname
        ,sc.DB
        ,sc.DOLS
        ,sc.dlnum
        ,Cons.Description AS ConS
        ,Conc.Description AS ConC
        ,'False' as Assigned
    FROM    [monitor].[uxref] xref 
    JOIN [Monitor].[dbo].[seacc] sc
        ON xref.regid = sc.[consid] 
    LEFT JOIN [Monitor].[dbo].Reg Cons ON Cons.RegID = sc.ConsId
    LEFT JOIN [Monitor].[dbo].Reg Conc ON Conc.RegID = sc.ConcId
    WHERE xref.UserId =1000


and 

 SELECT sc.clientid
        ,sc.dictionid
        ,sc.firstname 
        ,sc.lastname
        ,sc.DB
        ,sc.DOLS
        ,sc.dlnum
        ,Cons.Description AS ConS
        ,Conc.Description AS ConC
        ,'False' as Assigned
    FROM    [monitor].[uxref] xref 
    JOIN [Monitor].[dbo].[seacc] sc
        ON xref.regid = sc.[concid] 
    LEFT JOIN [Monitor].[dbo].Reg Cons ON Cons.RegID = sc.ConsId
    LEFT JOIN [Monitor].[dbo].Reg Conc ON Conc.RegID = sc.ConcId
    WHERE xref.UserId =1000


i.e.

 SELECT sc.clientid
        ,sc.dictionid
        ,sc.firstname 
        ,sc.lastname
        ,sc.DB
        ,sc.DOLS
        ,sc.dlnum
        ,Cons.Description AS ConS
        ,Conc.Description AS ConC
        ,'False' as Assigned
    FROM    [monitor].[uxref] xref 
    JOIN [Monitor].[dbo].[seacc] sc
        ON xref.regid = sc.[consid] 
    LEFT JOIN [Monitor].[dbo].Reg Cons ON Cons.RegID = sc.ConsId
    LEFT JOIN [Monitor].[dbo].Reg Conc ON Conc.RegID = sc.ConcId
    WHERE xref.UserId =1000
 UNION
 SELECT sc.clientid
        ,sc.dictionid
        ,sc.firstname 
        ,sc.lastname
        ,sc.DB
        ,sc.DOLS
        ,sc.dlnum
        ,Cons.Description AS ConS
        ,Conc.Description AS ConC
        ,'False' as Assigned
    FROM    [monitor].[uxref] xref 
    JOIN [Monitor].[dbo].[seacc] sc
        ON xref.regid = sc.[concid] 
    LEFT JOIN [Monitor].[dbo].Reg Cons ON Cons.RegID = sc.ConsId
    LEFT JOIN [Monitor].[dbo].Reg Conc ON Conc.RegID = sc.ConcId
    WHERE xref.UserId =1000