Delete rows on two different sheets based on cell value in a more efficient way [VBA Excel] - excel

Question

I have a two different worksheets with the same number of rows each one. In column R I have "New" or "Old" depending on the row (this is a dynamic value). What I want to do is, if a row in Worksheet1 contains "Old" in column R, then delete that row in both Worksheet1 and Worksheet2.
Now, I have tried two codes for this:
Dim w1 As Worksheet
Dim w2 As Worksheet
Set w1= Worksheets("Sheet1")
Set w2= Worksheets("Sheet2")
'-----------------------------------------------------
'Code 1
'-----------------------------------------------------
Application.ScreenUpdating = False
For r = w1.UsedRange.Rows.Count To 1 Step -1
If Cells(r, "R") = "Old" Then
w1.Rows(r).EntireRow.Delete
w2.Rows(r).EntireRow.Delete
End If
Next r
Application.ScreenUpdating = True
'-----------------------------------------------------
'Code 2
'-----------------------------------------------------
Dim i As Long
i = 1
Application.ScreenUpdating = False
Do While i <= w1.Range("R1").CurrentRegion.Rows.Count
If InStr(1, w1.Cells(i, 18).Text, "Old", vbTextCompare) > 0 Then
w1.Cells(i, 1).EntireRow.Delete
w2.Cells(i, 1).EntireRow.Delete
Else
i = i + 1
End If
Loop
Application.ScreenUpdating = True
Usually I have +800 rows, so Code 1 works as desired but it sometimes takes too long, like 3 minutes. Code 2 gets stuck so far.
What is an efficient way of doing this?

Answer 1

Delete Rows In Sheets
Implementing Union should considerably speed up the process.
The Code
Sub DeleteRowsInSheets()
Const cSheet1 As Variant = "Sheet1" ' First Worksheet Name/Index
Const cSheet2 As Variant = "Sheet2" ' First Worksheet Name/Index
Const cVntCol As Variant = "R" ' Search Column Letter/Number
Const cStrCriteria As String = "Old" ' Search Criteria String
Dim rngU1 As Range ' Union Range 1
Dim rngU2 As Range ' Union Range 2
Dim LastUR As Long ' Last Used Row
Dim i As Long ' Row Counter
With Worksheets(cSheet1)
' Calculate Last Used Row.
If .Cells.Find("*", .Cells(.Rows.Count, .Columns.Count), -4123, , 1) _
Is Nothing Then Exit Sub
LastUR = .Cells.Find("*", , , , , 2).Row
' Add found cells to Union Ranges.
For i = 1 To LastUR
If StrComp(.Cells(i, cVntCol), cStrCriteria, vbTextCompare) = 0 Then
If Not rngU1 Is Nothing Then
Set rngU1 = Union(rngU1, .Cells(i, 1))
Set rngU2 = Union(rngU2, Worksheets(cSheet2).Cells(i, 1))
Else
Set rngU1 = .Cells(i, 1)
Set rngU2 = Worksheets(cSheet2).Cells(i, 1)
End If
End If
Next
End With
' Delete rows.
If Not rngU1 Is Nothing Then
rngU1.EntireRow.Delete ' Hidden = True
rngU2.EntireRow.Delete ' Hidden = True
Set rngU2 = Nothing
Set rngU1 = Nothing
End If
End Sub

Answer 2

I think that there could be lots of formulas. So Application.Calculation = xlManual at the begining and Application.Calculation = xlCalculationAutomatic at the end should be good idea too.
Application.Calculation = xlCalculationManual
Application.ScreenUpdating = False
For r = w1.UsedRange.Rows.Count To 1 Step -1
If Cells(r, "R") = "Old" Then
w1.Rows(r).EntireRow.Delete
w2.Rows(r).EntireRow.Delete
End If
Next r
Application.ScreenUpdating = true
Application.Calculation = xlCalculationAutomatic