Alternate for Table.Group / Table.AggregateTableColumn, Slow power query data loading

Hi CMMaliniJoshi ,
just saw that you have an unbuffered reference to the table here still - that might cause the slow performance:
Added_Custom = Table.AddColumn(Changed_Type, "Day", each {Number.From([Maturity_Date])..Number.From(List.Max(dROI[Date_Upto]))}),

Cannot do any more here. Further help would need the data itself, but for me, this would then run into consultancy services that I would have to charge for.
You might want to consider opening separate threads for it and make sure to include sample data to it so folks can follow the desired logic.