Highlight Duplicates between two ranges on different worksheets

Question

I'm trying to find a more efficient way to highlight duplicate cells between two ranges on different worksheets. The code below is painfully slow:

    Sub HighlightDuplicates()
Application.DisplayAlerts = False

lrU = Sheets("Sheet1").Cells(Rows.Count, 1).End(xlUp).Row
lrPT = Sheets("Sheet2").Cells(Rows.Count, 1).End(xlUp).Row

Dim rng1, rng2, cell1, cell2 As Range

Set rng1 = Worksheets("Sheet1").Range("DL4:DL" & lrU)
Set rng2 = Worksheets("Sheet2").Range("E3:M" & lrPT)

    For Each cell1 In rng1

        For Each cell2 In rng2

            If cell1.Value = cell2.Value Then

            cell1.Font.Bold = True
            cell1.Font.ColorIndex = 2
            cell1.Interior.ColorIndex = 3
            cell1.Interior.Pattern = xlSolid
            cell2.Font.Bold = True
            cell2.Font.ColorIndex = 2
            cell2.Interior.ColorIndex = 3
            cell2.Interior.Pattern = xlSolid

            End If

        Next cell2
     Next cell1
Application.DisplayAlerts = True
End Sub

Any suggestions on a more efficient method?

Thanks for any help.

Regards,

Answer 1

Putting my comments together, you could modify your code to look something like this (untested)

Sub HighlightDuplicates()
Application.DisplayAlerts = False
application.calculation=xlcalculationmanual
application.screenupdating=false

lrU = Sheets("Sheet1").Cells(Rows.Count, 1).End(xlUp).Row
lrPT = Sheets("Sheet2").Cells(Rows.Count, 1).End(xlUp).Row

Dim rng1, rng2, cell1, cell2 As Range

Set rng1 = Worksheets("Sheet1").Range("DL4:DL" & lrU)
Set rng2 = Worksheets("Sheet2").Range("E3:M" & lrPT)

For Each cell2 In rng2
    Set cell1 = rng1.Find(cell2, lookin:=xlValues)
    if not cell1 is nothing then
        firstAddress = cell1.address
        Do
            cell1.Font.Bold = True
            cell1.Font.ColorIndex = 2
            cell1.Interior.ColorIndex = 3
            cell1.Interior.Pattern = xlSolid
            cell2.Font.Bold = True
            cell2.Font.ColorIndex = 2
            cell2.Interior.ColorIndex = 3
            cell2.Interior.Pattern = xlSolid
            Set cell1 = rng1.FindNext(cell2)
        Loop While Not cell1 Is Nothing And cell1.Address <> firstAddress 
    end if
next cell1

application.displayalerts=true
application.calculation=xlcalculationmanual
application.screenupdating=true
end sub