Excel Slow performance

[Svmaxcel]

Sub M_snb() 
  sn = Sheets("Data").Cells(1).CurrentRegion 
  sp = Sheets("Mapping").UsedRange 
  sf= split("dddd_'mmm-yy_\Wk ww_\WB dd-mm-yyyy_\WE dd-mm-yyyy","_")
 
  For j = 2 To UBound(sn) 
    For jj = 2 To UBound(sp) 
      If sn(j, 3) = sp(jj, 1) Then Exit for
    next
    sn(j, 17) = sp(jj, 2) 
    sn(j, 18) = sp(jj, 4) 
    sn(j, 19) = sp(jj, 5) 
         
    For jj = 2 To UBound(sp) 
      If sn(j, 1) = sp(jj, 16) Then exit for
    next
    sn(j, 20) = sp(jj, 20) 
    sn(j, 21) = sp(jj, 21) 
         
    w_00 = sn(j, 2) - Weekday(sn(j, 2)) 
    For jj = 22 To 28 
      If jj < 27 Then sn(j, jj - 10) = Format(Choose(jj - 21, sn(j, 2), sn(j, 2), sn(j, 2), w_00 + 1, w_00 + 7), sf(jj - 21)) 
      sn(j, jj) = Choose(jj - 21, sn(j, 5) * sn(j, 4), sn(j, 6) * sn(j, 4), sn(j, 7) * sn(j, 4), sn(j, 8) * sn(j, 4), sn(j, 9) / 600, sn(j, 10) / 60, sn(j, 11) / 60) 
    Next 
  Next 
     
  Sheets("Data").Cells(1).CurrentRegion.Offset(19) = sn 
End Sub

The code didn't get through properly, I copied the code and got error variable or block variable not found.
While stepping it has a error on sn(j, 17) = sp(jj, 2)