MEASUREMENT OPTIMIZATION USING SUMX

Hi Paula1323 
Using variables will speed it a little. However, without further details won't be able to provide you with a definitive answer. Seems like the row level SUMX can be avoided at least the measures inside it can be avoided.

Generated Reduced PT =
IF (
    HASONEVALUE ( 'Generated PT'[BK_MISSION] ),
    VAR Case1 = [Case_1]
    VAR Case2 = [Case_2]
    VAR Case3 = [Case_3]
    VAR Case4 = [Case_4]
    VAR Case5 = [Case_5]
    VAR Case6 = [Case_6]
    RETURN
        SWITCH (
            TRUE (),
            Case1 > 0, Case1,
            Case2 > 0, Case2,
            Case3 > 0, Case3,
            Case4 > 0, Case4,
            Case5 > 0, Case5,
            Case6 > 0, Case6
        ),
    CALCULATE (
        SUMX (
            'Mission (Attributes)',
            VAR Case1 = [Case_1]
            VAR Case2 = [Case_2]
            VAR Case3 = [Case_3]
            VAR Case4 = [Case_4]
            VAR Case5 = [Case_5]
            VAR Case6 = [Case_6]
            RETURN
                SWITCH (
                    TRUE (),
                    Case1 > 0, Case1,
                    Case2 > 0, Case2,
                    Case3 > 0, Case3,
                    Case4 > 0, Case4,
                    Case5 > 0, Case5,
                    Case6 > 0, Case6
                )
        ),
        FILTER ( 'Mission (Attributes)', 'Mission (Attributes)'[Company] = "PT" )
    )
)