Macro freezing excel when comparing 2 worksheets for duplicates

[SBMa]

I have a macro that imports a worksheet and compares it for duplicates in the current worksheet before copying the data.
It works for small data sets but freezes when ran on the workbook I created it for as it has a very large data set (100,000 rows+).

Need help optimising my code or fixing this please.
Any help is greatly appreciated

Sub DownloadImportAndCheckDuplicates()

'

Dim fileToOpen As Variant
Dim fileFilterPattern As String
Dim wsMaster As Worksheet
Dim wbTextImport As Workbook

Dim dlr As Long
Dim lr As Long
Dim lImpC As Long
Dim lImpR As Long
Dim countMatch As Boolean
Dim concat As Collection

Set concat = New Collection

Application.ScreenUpdating = False

Set wsMaster = ThisWorkbook.Worksheets("Download Data")
    
  With wsMaster
    lr = .Cells(Rows.Count, 1).End(xlUp).Offset(1).Row
    dlr = .Cells(Rows.Count, 1).End(xlUp).Row
    
    ' adds date downloaded, asset name & email to collection
    For i = 5 To dlr
      concat.Add .Cells(i, 1) & "__" & .Cells(i, 2) & "__" & .Cells(i, 3)
    Next i
  End With
  

fileFilterPattern = "Microsoft Excel Workbooks (*.xls*),*.xls*"

fileToOpen = Application.GetOpenFilename(fileFilterPattern)

' open workbook

If fileToOpen = False Then
  ' input Cancelled
  MsgBox "No file Selected."
Else

  Workbooks.OpenText _
    Filename:=fileToOpen, _
    StartRow:=2, _
    DataType:=xlDelimited, _
    Tab:=True

  Set wbTextImport = ActiveWorkbook
  
' limpC last column with data
' limmpR last row with data
  With wbTextImport.Worksheets(1)
    lImpC = .Cells(1, .Columns.Count).End(xlToLeft).Column
    lImpR = .Cells(Rows.Count, 1).End(xlUp).Row
    
    arrdata = .Range("A1:C" & lImpR).Value
  End With
End If


countMatch = False
Dim j As Long

' nested loop comparing the concatenated string from asset upload data and 3d array of imported text
For i = LBound(arrdata) To UBound(arrdata) ' I'm assuming the data copied has headers, if not, change 2 for 1
  For j = 1 To concat.Count
'Debug.Print concat(j) & "        concat"
'Debug.Print (arrdata(i, 1) & "__" & arrdata(i, 2) & "__" & arrdata(i, 3)) & "           toCompare"
    
    If concat(j) = (arrdata(i, 1) & "__" & arrdata(i, 2) & "__" & arrdata(i, 3)) Then
      MsgBox "Duplicates found, please check data you are attempting to copy"
      countMatch = True
      
      GoTo LastLine
      
    Else
' If no duplicates import worksheet from a2 to last cells with data on this worksheet from lr in c
      If countMatch = False And i = UBound(arrdata) Then
        With wbTextImport.Worksheets(1)
          .Range("A2", .Cells(lImpR, lImpC)).Copy wsMaster.Range("A" & lr)
        End With
    
        
      End If
    End If
  Next j
Next i

LastLine:
  Debug.Print "We're out"
wbTextImport.Close False
    
Application.ScreenUpdating = True
'
End Sub

 

[Joe4]

To be quite honest with you, I think it may be a bit too much for Excel to handle.
I would probably look at using something like Microsoft Access for doing this instead.