🚀 go-pugleaf

Environment.  IB 7.5.1
It takes almost 25% cpu on a 4 processor machine with licens for 2 
processors.
1.Can someone explain why?
2. Can this sql be done in another way?

Within one sessionID (and logid). Show only the rows with the highest event 
and status.

EVENT   STATUS
1                -1
2                -1
3                1, 2, 3, 4, 5



Select
    Pot, Env, SessionID, LogId, Resent, SenderN, ReceiverN, Doctype, Event, 
Status, ' ' as TransferStatus, RowID, 'More info..' as Details
From
    Transferlog o
Where

  o.Pot between '2008-01-29 00:41:25' and '2008-01-29 23:59:59'
 and Env = 'xib'
and

(
    (o.Event = 3 and o.Status =
       (Select max(Status) from Transferlog i
           where i.env = o.env and i.SessionID = o.SessionID and i.logid = 
o.logid))
  or
    (o.Event = 2 and not exists
       (select SessionId from Transferlog x
           where x.env = o.env and x.sessionid = o.sessionid and x.event > 2 
and x.logid = o.logid))
  or
    (o.Event = 1 and not exists
       (select SessionId from transferlog y
           where y.env = o.env and y.sessionid = o.sessionid and y.event > 
1))
)
order by 1 Descending, 2 Descending, 3 Descending

Plan
PLAN (I INDEX (TRANSFERLOG_IX30))
PLAN (X INDEX (TRANSFERLOG_IX80))
PLAN (Y INDEX (TRANSFERLOG_IX80))
PLAN SORT ((O INDEX (TRANSFERLOG_IX45)))

Adapted Plan
PLAN (I INDEX (TRANSFERLOG_IX30)) PLAN (X INDEX (TRANSFERLOG_IX80)) PLAN (Y 
INDEX (TRANSFERLOG_IX80)) PLAN SORT ((O INDEX (TRANSFERLOG_IX45)))