slow code

[daveyc18]

this is running slowing....could someone pls recommend a way to speed this up? im afraid of doing calculation xlmanual....will that mena the loops wont work?

    Dim chk As String
    Dim amtc
    Dim found As String
    Dim clear_c As Integer  'total record count on "Cleared" sheet
    Dim os_c As Integer     'total record count on "Outstanding Cheques" sheet
    Dim nf_c As Integer     'total record count on "Cleared Not Outstanding" sheet
    Dim nf_r As Range
    
    
    'Clear "Cleared Not Outstanding" data
    Sheets("Cleared-Not-In-Outstanding").Select
    Selection.CurrentRegion.ClearContents
    Range("A1") = "Reference"
    Range("B1") = "Gross Amount"
    
    'Count total number of records on "Outstanding Cheques" sheet
    Sheets("Outstanding_Cheques").Select
    os_c = Range("A6").CurrentRegion.Rows.Count
    
    'Count total number of records on "Cleared" sheet
    Sheets("Cleared").Select
    clear_c = Range("A1").CurrentRegion.Rows.Count
    
    'Loop through each record on "Clear" sheet.
    'Check to see if the record exists on "Outstanding" sheet.
    For I = 1 To clear_c
      Let found = "False"
      chk = ActiveCell.Offset(I - 1, 0).Value
      amtc = ActiveCell.Offset(I - 1, 1).Value
        
        Sheets("Outstanding_Cheques").Select
        Range("A6").Select
        For y = 1 To os_c - 1
        'If the value reference and amount agree, cut the cleared cheque from the outstandings list and move it to cashed
          If (ActiveCell.Offset(y - 1, 1).Value = chk) And (ActiveCell.Offset(y - 1, 2).Value = amtc) Then
            ActiveCell.Offset(y - 1, 0).Select
            ActiveCell.EntireRow.Cut Sheets("Cashed").Range("A65536").End(xlUp).Offset(1, 0)
            ActiveCell.EntireRow.Delete
            os_c = os_c - 1
            Let found = "True"
            Exit For
          End If
        Next y
        
        'If the cleared cheque doesn't match any items in the outstanding list, paste the data on the cleared not os sheet
        If found = "False" Then
          Sheets("Cleared-Not-In-Outstanding").Select
          Range("A1").Select
          nf_c = Range("A1").CurrentRegion.Rows.Count
          ActiveCell.Offset(nf_c, 0).Value = chk
          ActiveCell.Offset(nf_c, 1).Value = amtc
           
        End If
      
      
      Sheets("Cleared").Select
      Range("A1").Select


Next I


'update cashed tab
Dim clear_date As String


clear_date = Range("D1")


 
 Sheets("Cashed").Select
 Range("e65536").End(xlUp).Activate
 ActiveCell.Offset(1, 0).EntireRow.Insert
 ActiveCell.Offset(2, 0).Select
 Do


    ActiveCell.Value = clear_date


    ActiveCell.Offset(1, 0).Select


    Loop Until IsEmpty(ActiveCell.Offset(0, -1))


Sheets("Reconciliation").Select
Range("d3").Select