after add two statement stuff query executing take long time as 5 min

Question

I work on SQL server 2014 after add two stuff statement to script below

it become very slow

before add two stuff statement it take 28 second for display 500 thousand

now as below script and after add two statement stuff take 5 minutes

so how to solve issue please

my script as below :

IF OBJECT_ID('[dbo].[gen]') IS NOT NULL
 DROP TABLE [dbo].[gen]
 IF OBJECT_ID('[dbo].[PartAttributes]') IS NOT NULL
 DROP TABLE [dbo].[PartAttributes]
 IF OBJECT_ID('dbo.core_datadefinition_Detailes') IS NOT NULL
 DROP TABLE core_datadefinition_Detailes

 CREATE TABLE core_datadefinition_Detailes(
     [ID] [int] IDENTITY(1,1) NOT FOR REPLICATION NOT NULL,
     [ColumnName] [nvarchar](500) NOT NULL,
     [ColumnNumber] [int] NOT NULL,

  CONSTRAINT [PK_Core_DataDefinition_Details] PRIMARY KEY CLUSTERED
 (
     [ID] ASC
 )
 )
 insert into core_datadefinition_Detailes([ColumnNumber],[ColumnName])
 values
 (202503,'Product Shape Type'),
 (1501170111,'Type'),
 (202504,'Package Family')

 CREATE TABLE [dbo].[gen](
     [TradeCodeControlID] [int] IDENTITY(1,1) NOT NULL,
     [CodeTypeID] [int] NULL,
     [RevisionID] [bigint] NULL,
     [Code] [varchar](20) NULL,
     [ZPLID] [int] NULL,
     [ZfeatureKey] [bigint] NULL,
 ) ON [PRIMARY]
 GO
 SET IDENTITY_INSERT [dbo].[gen] ON
 INSERT [dbo].[gen] ([TradeCodeControlID], [CodeTypeID],[RevisionID],  [Code], [ZPLID], [ZfeatureKey]) VALUES (7565,  849774, 307683692, N'8541100050', 4239, 202503)
 INSERT [dbo].[gen] ([TradeCodeControlID], [CodeTypeID],[RevisionID],  [Code], [ZPLID], [ZfeatureKey]) VALUES (7566,  849774, 307683692, N'8541100050', 4239, 202504)
 INSERT [dbo].[gen] ([TradeCodeControlID], [CodeTypeID],[RevisionID],   [Code], [ZPLID], [ZfeatureKey]) VALUES (7567,  849774, 307683692, N'8541100050', 4239, 1501170111)
 SET IDENTITY_INSERT [dbo].[gen] OFF

 CREATE TABLE [dbo].[PartAttributes](
     [PartID] [int] NOT NULL,
     [ZfeatureKey] [bigint] NULL,
     [AcceptedValuesOption_Value] [float] NULL,
     [FeatureValue] [nvarchar](500) NOT NULL
 ) ON [PRIMARY]

 GO
 INSERT [dbo].[PartAttributes] ([PartID], [ZfeatureKey],  [FeatureValue]) VALUES (413989, 202503, N'Discrete')
 INSERT [dbo].[PartAttributes] ([PartID], [ZfeatureKey],  [FeatureValue]) VALUES (413989, 1501170111, N'Zener')
 INSERT [dbo].[PartAttributes] ([PartID], [ZfeatureKey],  [FeatureValue]) VALUES (413989, 202504, N'SOT')

 SELECT  PartID,Code,Co.CodeTypeID,Co.RevisionID,Co.ZPLID,Count(1) as ConCount,
                 stuff(( SELECT  '$' + CAST( CP.ColumnName AS VARCHAR(300)) AS [text()]
                     FROM(SELECT distinct d.ColumnName,C.codeTypeId,C.Code,C.ZfeatureKey from gen C
                     inner join core_datadefinitiondetails d with(nolock) on C.ZfeatureKey=d.columnnumber
                     INNER JOIN PartAttributes P on P.partid=PM.partid)CP
                     where CP.codeTypeId=Co.codeTypeId and CP.Code=Co.Code
                     ORDER BY CP.ZfeatureKey

                     FOR XML PATH(''), TYPE
                      ).value('.', 'NVARCHAR(MAX)')
                         , 1,  1, '') as FeatureName,
                         stuff(( SELECT  '$' + CAST( CP2.FeatureValue AS VARCHAR(300)) AS [text()]
                     FROM(SELECT distinct P.FeatureValue,C2.codeTypeId,C2.Code,C2.ZfeatureKey FROM gen C2
                     INNER JOIN PartAttributes P on C2.ZfeatureKey=P.ZfeatureKey)CP2
                     where CP2.codeTypeId=Co.codeTypeId and CP2.Code=Co.Code
                     ORDER BY CP2.ZfeatureKey
                     FOR XML PATH(''), TYPE
                      ).value('.', 'NVARCHAR(MAX)')
                         , 1,  1, '') as FeatureValue
                 FROM
                 PartAttributes PM
                 INNER JOIN    gen Co ON Co.ZfeatureKey = PM.ZfeatureKey Group By PartID,Code,Co.CodeTypeID,Co.RevisionID,Co.ZPLID

                 select * from alldata

expected result as below :

PartID	Code	CodeTypeID	RevisionID	ZPLID	ConCount	FeatureName	FeatureValue
413989	8541100050	849774	307683692	4239	3	Product Shape Type$Package Family$Type	Discrete$SOT$Zener