title: VBA Macro extremely slow: 15 min runtime
body: <p>This is my code, it takes some values from a file, looks them up in another file and pastes a value in the row where it fins those values. My file tg has 126 lines and 135 columns. My file gar_nv has 2553 lines and 67 columns. My variable nbrLines is equal to 2553.
  It takes 15 min to finish running. I'm wondering which part is making it so slow ? Or is it because of how big my sheets are. Thanks</p>
  <pre><code>Sub Remb()
  Call Workbook_open
  
  Dim acte, acte_next, Remb, Col, Col_next, produit As Variant
  Dim colonne, ligne, Line, r, c As Long
  
  With tg
  
     For colonne = col_dep To .UsedRange.Columns.Count
      
          For ligne = ligne_dep To nbrLines
          
              acte = tg.Range(ColName(colonne) &amp; ligne)
              r = ligne
              c = Columns(ColName(colonne)).Column
              MsgBox (acte)
                  
              
              If Not IsEmpty(acte) Then
                  Remb = .Cells(r, c).Offset(0, -1).Value 
                  Col = .Cells(r, c).Offset(0, 1).Value 
                  produit = .Cells(6, c).Value 
                  
                  acte_next = .Cells(r, c).Offset(1, 0).Value
                  Col_next = .Cells(r, c).Offset(1, 1).Value
                  
          
                  
                  For Line = 1 To gar_nv.Cells(Rows.Count, 1).End(xlUp).Row
                  
                      If gar_nv.Range(&quot;GCGAR6&quot;).Rows(Line).Value Like produit Then
                          If gar_nv.Range(&quot;GCBARB&quot;).Rows(Line).Value Like acte Then
                              
                             gar_nv.Range(Col).Rows(Line).Value = Remb
                             
                          End If
                      End If
                  Next Line
              End If
          Next ligne
      Next colonne
  End With
  End Sub
  </code></pre>