Public Sub TestSpeed()
    Dim inRange As Range, t As Single
    Dim vResult As Double, i As Long, vData As Variant
    Set inRange = ActiveSheet.Range("A1:A500")
    vData = inRange.Value
    t = Timer
    For i = 1 To 10000
        vResult = getMaxDescendingSequenceSumAnVG(vData)
    Next
    Debug.Print Timer - t
    t = Timer
    For i = 1 To 10000
        vResult = getMaxDescendingSequenceSumBMV(vData)
    Next
    Debug.Print Timer - t

End Sub

Public Function getMaxDescendingSequenceSumBMV(ByVal vData) As Double
    Dim v, i As Long
    'vData = inRange.Value
    v = vData
    For i = 2 To UBound(vData, 1)
        If vData(i, 1) < vData(i - 1, 1) Then _
            v(i, 1) = v(i - 1, 1) + vData(i, 1)
    Next
    getMaxDescendingSequenceSumBMV = Fix(Application.Max(v))
End Function

Public Function getMaxDescendingSequenceSumAnVG(ByVal vData) As Double
    Dim maxSum As Double, curSum As Double, v As Double, i As Long
    'vData = inRange.Value
    v = vData(1, 1)
    curSum = v
    maxSum = -1E+308
    For i = 2 To UBound(vData, 1)
        If vData(i, 1) < v Then
            curSum = curSum + vData(i, 1)
        Else
            If maxSum < curSum Then maxSum = curSum
            curSum = vData(i, 1)
        End If
        v = vData(i, 1)
    Next
    If maxSum < curSum Then maxSum = curSum
    getMaxDescendingSequenceSumAnVG = Fix(maxSum)
End Function

Public Function getMaxDescendingSequenceSumAnVG(ByVal vData) As Double
    Dim maxSum As Double, curSum As Double, v As Double, p As Double, i As Long
    'vData = inRange.Value
    p = vData(1, 1)
    curSum = p
    maxSum = -1E+308
    For i = 2 To UBound(vData, 1)
        v = vData(i, 1)
        If v < p Then
            curSum = curSum + v
        Else
            If maxSum < curSum Then maxSum = curSum
            curSum = v
        End If
        p = v
    Next
    If maxSum < curSum Then maxSum = curSum
    getMaxDescendingSequenceSumAnVG = Fix(maxSum)
End Function