Stuff function in SQL takes more time

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SQL

I'm Concatenate string values using Stuff function. But this takes more time to execute.When I google, I came to know two ways 1.Indexing and 2. Cross Apply both Method I implemented in my query. But still it takes more time. How can i optimize the stuff function? Is there any other solution Available?

What I have tried:

SELECT p1.Data,
		STUFF((SELECT '-'+ Res 
               FROM View1 p2
               WHERE p2.Id = p1.Id 
			   Order by __seq__ID
               FOR XML PATH(''))
            ,1,1,'') AS 'Newcolumn'
		
FROM View1 p1