Why REPLACE query is taking so much time in SQL Server 2008 - sql-server

Question

I Have a SQL query which converts the date time to 106 format and after that I am replacing the blank space to - which takes too much time almost 4 min while executing . Example as follows
REPLACE(CONVERT(VARCHAR,GETDATE(),106),' ','-') DDate
Output 19-Feb-2015
Without replace my query is taking 0 second
Is there any another way to get the custom format dates as mentioned above ?
I understood that REPLACE will compare the collection of result items.
But it should not take 4 min to replace 100 to 200 data.
Any thoughts?
Query as
SELECT TOP(ISNULL(100,'10000'))
FD.Flight 'Select'
,FD.Filename
,ISNULL(FD.RefNo, 'FLT-' + CONVERT(VARCHAR, FD.FLID)) 'FlightID'
,FD.Registration
,ISNULL(FD.FlightNumber, '') FlightNumber
**,REPLACE(CONVERT(VARCHAR,FD.TKD,106),' ','-') TODate**
,FD.TOGMT
**,REPLACE(CONVERT(VARCHAR,FD.LKD,106),' ','-') LDDate**
,FD.LDGMT
,FD.Origin
,FD.Destination
,FD.Pilot
,FD.CoPilot
**,REPLACE(CONVERT(VARCHAR,FD.DumpDate,106),' ','-') DDate**
,FD.UserName
,FD.FlightCount
,FD.AcVariation
FROM
dbo.vw_FlightDetails FD
LEFT JOIN [dbo].FlightRemark RM ON RM.FlightID = FD.FLID
WHERE
1=1
ORDER BY
FD.TKD DESC
,FD.TOGMT DESC
Bold Area is the problem i am facing

Answer 1

It's hard to tell what's happening here, but you can try this:
select <all your _other_ columns>,
ISNULL(x.RefNo, 'FLT-' + CONVERT(VARCHAR, x.FLID)) FlightID,
REPLACE(CONVERT(VARCHAR, x.TKD, 106),' ','-') TODate,
REPLACE(CONVERT(VARCHAR, x.LKD, 106),' ','-') LDDate,
REPLACE(CONVERT(VARCHAR, x.DumpDate, 106),' ','-') DDate,
from (
SELECT TOP (ISNULL(100,'10000'))
FD.Flight 'Select'
,FD.Filename
,FD.RefNo,
,FD.FLID
,FD.Registration
,ISNULL(FD.FlightNumber, '') FlightNumber
,FD.TKD
,FD.TOGMT
,FD.LKD
,FD.LDGMT
,FD.Origin
,FD.Destination
,FD.Pilot
,FD.CoPilot
,FD.DumpDate
,FD.UserName
,FD.FlightCount
,FD.AcVariation
FROM
dbo.vw_FlightDetails FD
LEFT JOIN [dbo].FlightRemark RM ON RM.FlightID = FD.FLID
WHERE
1=1
ORDER BY
FD.TKD DESC
,FD.TOGMT DESC
) x
basically, bury the query into a subquery, then format the dates only on the resulting rows. I suspect this is happening because of the top() statement... it is probably processing many more rows with the REPLACE than it needs to.