Slow macro hiding rows based on value - vba

Question

I have a table that I want to completely hide or hide/show rows within the table, depending on whether a cell value is 0 or above.
It looks for a value of 0 within cell D26; if 0 it hides rows 24-51, if not 0 it hides/shows rows depending on whether there is a value in the C column between rows 34 and 49.
The macro below is too slow to be a viable option. Can anyone suggest an alternative way of doing this, that might work in a few seconds rather than a few minutes? I think it's because I'm running the For/If/Else loop.
Sub HideManifolds()
'
' HideManifolds Macro
'
Application.ScreenUpdating = False
Application.EnableEvents = False
Application.Calculation = xlCalculationManual
ChkCol = 3
Manifold1BeginTableRow = 34
Manifold1EndTableRow = 49
Manifold1BeginRow = 24
Manifold1EndRow = 51
For Manifold1RowCnt = Manifold1BeginRow To Manifold1EndRow
If Cells(26, 4).Value = 0 Then
Cells(Manifold1RowCnt, 1).EntireRow.Hidden = True
Else
For Manifold1TableRowCnt = Manifold1BeginTableRow To Manifold1EndTableRow
If Cells(Manifold1TableRowCnt, ChkCol).Value = 0 Then
Cells(Manifold1TableRowCnt, ChkCol).EntireRow.Hidden = True
Else
Cells(Manifold1TableRowCnt, ChkCol).EntireRow.Hidden = False
End If
Next Manifold1TableRowCnt
End If
Next Manifold1RowCnt
Application.ScreenUpdating = True
Application.EnableEvents = True
Application.Calculation = xlCalculationAutomatic
'
End Sub

Answer 1

I think you don't need this loop For Manifold1RowCnt = Manifold1BeginRow To Manifold1EndRow
code:
Sub HideManifolds()
'
' HideManifolds Macro
'
Dim hRng As Range, vRng As Range
Application.ScreenUpdating = False
Application.EnableEvents = False
Application.Calculation = xlCalculationManual
ChkCol = 3
Manifold1BeginTableRow = 34
Manifold1EndTableRow = 49
Manifold1BeginRow = 24
Manifold1EndRow = 51
If Cells(26, 4).Value = 0 Then
Rows(Manifold1BeginRow & ":" & Manifold1EndRow).Hidden = True
Else
For Manifold1TableRowCnt = Manifold1BeginTableRow To Manifold1EndTableRow
If Cells(Manifold1TableRowCnt, ChkCol).Value = 0 Then
If hRng Is Nothing Then
Set hRng = Cells(Manifold1TableRowCnt, ChkCol)
Else
Set hRng = Union(hRng, Cells(Manifold1TableRowCnt, ChkCol))
End If
Else
If vRng Is Nothing Then
Set vRng = Cells(Manifold1TableRowCnt, ChkCol)
Else
Set vRng = Union(vRng, Cells(Manifold1TableRowCnt, ChkCol))
End If
End If
Next Manifold1TableRowCnt
If Not hRng Is Nothing Then hRng.EntireRow.Hidden = True
If Not vRng Is Nothing Then vRng.EntireRow.Hidden = False
End If
Application.ScreenUpdating = True
Application.EnableEvents = True
Application.Calculation = xlCalculationAutomatic
'
End Sub