One thing to watch out for with Union is that it becomes exponentially
slower if/as the number of discontiguous areas in the unioned range
increase. Typically it's faster to process batches of 50-400 areas at a
time. The exact qty of areas depends on what the process is but a good rule
of thumb is limit to about 80-100.

The following should demonstrate the difference, trying to union 20k areas
is not viable.

Sub UnionDemo()
Dim bFastTest As Boolean
Dim bGotRng As Boolean
Dim i As Long
Dim arr() As Long
Dim rHide As Range

Rows.Hidden = False
Columns(1).Clear

Set rng = Range("A1:A40000")

ReDim arr(1 To rng.Rows.Count, 1 To 1)
For i = 1 To UBound(arr) Step 2
arr(i, 1) = 1
Next

rng.Value = arr

bFastTest = True
' bFastTest = False ' reduce rng size above to say 4k or less for
testing

t = Timer ' sensitive timer not required !

If bFastTest Then

For Each cell In rng
If cell.Value = 0 Then
If bGotRng Then
Set rHide = Union(rHide, cell)
If rHide.Areas.Count 100 Then
rHide.EntireRow.Hidden = True
Set rHide = Nothing
bGotRng = False
End If
Else
Set rHide = cell
bGotRng = True
End If
End If
Next

If Not rHide Is Nothing Then ' or If bGotRng ...
rHide.EntireRow.Hidden = True
End If

Else ' do ctrl-break if it's taking to long
Set rHide = Nothing
For Each cell In rng
If cell.Value = 0 Then
If rHide Is Nothing Then
Set rHide = cell
Else
Set rHide = Union(rHide, cell)
End If
End If
Next

If Not rHide Is Nothing Then
rHide.EntireRow.Hidden = True
End If

End If
Debug.Print Timer - t

End Sub

Regards,
Peter T


"Rick Rothstein (MVP - VB)" wrote in
message ...
I know you have a different solution now, but your comment about the speed
of the code I posted for you earlier got me to thinking. Probably the
speed
problem is due to the continual hiding of the rows one-by-one. I'm
thinking
the code below should be more efficient. If you have the chance, I would
be
interested in how fast the code below is compared to the code I gave you
earlier.

Sub HideRowIfZeroInJ()
Dim R As Range
Dim RowsToHide As Range
Dim LastRow As Long
Application.ScreenUpdating = False
With Worksheets("Sheet3")
LastRow = .Cells(Rows.Count, "J").End(xlUp).Row
For Each R In .Range("J3:J" & CStr(LastRow))
If R.Value = 0 And R.Value < "" Then
If RowsToHide Is Nothing Then
Set RowsToHide = R
Else
Set RowsToHide = Union(R, RowsToHide)
End If
End If
Next
If Not RowsToHide Is Nothing Then RowsToHide.EntireRow.Hidden = True
End With
Application.ScreenUpdating = True
End Sub

Rick

<snip