Duplicate or refer Table ? Or someting else

Hello,

Here is my M-code for one of the queries to create my columns and it takes too much time (around 10 mn)

I follow the same steps for other columns

Just for information my Table1 takes around 50 sec to add the 38 columns to the original source

my key_1 and key_2 are Text and I sum quantities

        #"join_sum_T1_T2_" = let

            #"GroupedLines" = Table.Group(Table.SelectColumns(Table.SelectRows(Table1, (sel)=> sel[#"filter_item"] = 1),{"key_1", "field_1", "field_2", "field_3", "field_4", "field_5"}), {"key", "filter_item"}, {{"sum_field_1", each List.Sum([#"field_1"]), type nullable number}, {"sum_field_2", each List.Sum([field_32), type nullable number}, {"Ssum_field_3", each List.Sum([#"field_3"]), type nullable number}, {"sum_field_4", each List.Sum([#"field_4"]), type nullable number}}),

            #"MergedQueries" = Table.NestedJoin(#"Table2_source", {"key_2"}, #"GroupedLines", {"key_1"}, "Table1_sum", JoinKind.LeftOuter),

            #"Tableexpanded" = Table.ExpandTableColumn(#"MergedQueries", "Table1_sum", {"sum_field_1", "sum_field_2", "sum_field_3", "sum_field_4"}, {"sum_field_1", "sum_field_2", "sum_field_3", "sum_field_4"})

            in
            #"Tableexpanded",

The equivalent SQL code would be:

        with GroupedLines as (select key, sum(field_1) as sum_field_1, sum(field_2) as sum_field_2, sum(field_3) as sum_field_3, sum(field_4) as sum_field_4 
        from Table1
        where filter_item = 1
        group by key)
        select * from Table2_source
        left join GroupedLines
        on key_1 = key_2

Thanks

Kind regards