Rolling totals and averages formula efficiency

[dicken]

Hi,

does anyone have any views on

Rolling Total :=
VAR tdate =
    MAX ( Alls[Dates] )
RETURN
   AVERAGEX  ( FILTER ( ALLSELECTED ( Alls[Dates] ), Alls[Dates] <= tdate ), [Tsales] )

Versus

Rollingtotal2 :=
VAR maxd =
    MAX ( Alls[Dates] )
RETURN
    CALCULATE ( [Average], FILTER ( ALL ( Alls[Dates] ), Alls[Dates] <= maxd ) )

and if one method might be better ?
Richard