Option Explicit
Private Declare Function timeGetTime Lib "winmm.dll" () As Long
Function NotEmptyCells(b As Range) As Long
    Dim i As Long, j As Long, k As Long
    Dim A As Variant
    A = b
    For i =  1  To UBound(A,  1 )
        For j =  1  To UBound(A,  2 )
            If IsEmpty(A(i, j)) = False Then k = k +  1 
        Next j
    Next i
    NotEmptyCells = k
End Function
Sub Proverka()
    Dim i  As Long, j As Long, k As Long
    Dim Main As Object
    Dim Chislo( 1  To  2 ) As Long
    ''Задаем Main
    Set Main = Workbooks("").Sheets("")
    ''
    i = timeGetTime
        Chislo( 1 ) = NotEmptyCells(Main.Range("A1:IV30000"))
    j = timeGetTime
        Chislo( 2 ) = WorksheetFunction.CountA(Main.Range("A1:IV30000"))
    k = timeGetTime
    MsgBox "Функция NotEmptyCells обнаружила в диапазоне " _
    & Chislo( 1 ) & " записей за " & j - i & "мс" & vbCrLf & _
    "Функция CountA обнаружила в диапазоне " & Chislo( 2 ) & " записей за " & k - j & "мс"
End Sub