You need the ORDER BY, otherwise what TOP returns is unpredictable.

You also need the reference to table trans in the subselect because the [order] table is filtered by a different set of trans rows than the main query.

What indexes do you have on both tables? Can you post the actual execution plan?

SELECT

x.[Route],

T1.[To license number. (/TO_LIC)] as TO_LIC,

T1.[From license number.] AS FROM_LIC,

T1.TO_ITEM,

T1.FROM_LOCATION,

T1.TO_LOCATION,

T1.[Transaction type.] AS TransType,

T1.[Populates by TRANS_NO_SEQ to generate a uniqu] as TransNo,

T1.[ORD_NO] as OrderNO,

T1.[Refers to ORD_KEY in ORD_MAST.] as ORD_KEY,

T1.[References LOAD_ID in ORD_MAST.] as Load_ID_ORD_MAST,

T1.[Date record was created.],

CASE

WHEN (T1.to_location like 'INN_MONO%BANE%' OR T1.to_location like 'INN_MONO_ORM%')

THEN 'INFEED'

WHEN (T1.to_location like 'INN_MONO%' OR T1.to_location like 'PRE_MONO_ORM%')

THEN 'FLOOR'

WHEN (T1.to_location like 'TROLLEY%')

THEN 'TROLLEY'

WHEN T1.to_location like 'STG%' OR T1.to_location like 'UT%GULV'

THEN 'STAGED'

WHEN (T1.to_location like 'UT_RC_AVSLAG%' OR T1.to_location like 'UT_OPPLAST%')

THEN 'OUTFEED'

ELSE 'UNKNOWN'

END as Category

FROM TRANS as T1

CROSS APPLY (

SELECT TOP 1

[Route] = OM.ord_route

FROM TRANS T

INNER JOIN [ORDER] OM

ON OM.ord_key = T.[Refers to ORD_KEY in ORD_MAST.]

WHERE T.[From license number.] = T1.[From license number.]

AND T.[Transaction type.] = 014

AND (T.[Date record was created.] > T1.[Date record was created.]

AND T.[Date record was created.] < T1.[Date record was created.] + 1)

-- ORDER BY ...

) x

WHERE T1.[From license number.] like '4%'

and T1.[From license number.] not like '49%'

and T1.to_item not like 'Z%'

AND (

T1.to_location like 'INN_MONO%'

OR (T1.from_location like 'INN_MONO%' AND T1.to_location like 'INN_MONO%BANE%'

OR (( T1.from_location like 'INN_MONO%BANE%' OR T1.from_location like 'INN_MONO_ORM%' OR T1.from_location like 'LOC_MG60001' AND T1.to_location like 'TROLLEY%')

OR ( T1.from_location like 'TROLLEY%' AND ( T1.to_location like 'UT_OPPLAST&' OR T1.to_location like 'UT_RC_AVSLAG%')

)

OR ((T1.from_location like 'UT_OPPLAST%' OR T1.from_location like 'UT_RC_AVSLAG%' OR T1.from_location like 'INN_MONO%')

AND (T1.to_location like 'STG%' OR T1.to_location like 'UT_OPPLAST%GULV' )

)

OR (T1.from_location like 'FULLRC_CO_EOL%' AND T1.to_location like 'INN_MONO_ORM%')

OR (T1.from_location like 'PRE_MONO_ORM%' AND T1.to_location like 'INN_MONO_ORM%')

))

)