question optimize sql query

good day I have a query where I use a merge in store procedure I have a screen that has 7 thousand records that I must insert or update, the detail is that the process lasts about 5 minutes and I want to see a way to do the most fast I have the code so:

for (var i=0;i<7000;i++){
 var registro1;
 var regisro2;
 var registro3;
 "EXEC test '"&registro1&"','"&registro2&"','"&registro3&"'";

}

my store procedure:

CREATE PROCEDURE Clasificaciones(
@registro1 varchar(7),
@registro2 varchar(18),
@registro3 varchar(2),
)
AS
BEGIN
    SET NOCOUNT ON

    MERGE tabla as TARGET
    USING(SELECT @registro1, @registro2, @registro3) AS SOURCE(registro1, registro2, registro3)
    ON (TARGET.registro1 = SOURCE.registro1 AND TARGET.registro2 = SOURCE.registro2)
    WHEN MATCHED THEN
        UPDATE SET regitro3 = SOURCE.registro3, 

    WHEN NOT MATCHED THEN
        INSERT (registro1,registro2,registro3)
        VALUES (SOURCE.regisro1, SOURCE.registro2, SOURCE.registro3);
END

about how is the code then if someone can tell me how it would do something similar that was faster?