I have a Macro I recorded it takes anywhere from 18 to 20 sec to run. how can I speed it up?



Sub TabLow()
'
' TabLow Macro
'

''PURPOSE: Determine how many seconds it took for code to completely run

Dim StartTime As Double
Dim SecondsElapsed As Double

'Remember time when macro starts
  StartTime = Timer
'*****************************



Application.ScreenUpdating = False
    Selection.NumberFormat = "@"
    For Each ThisCell In Selection
    If Len(ThisCell) < 10 Then
    ThisCell = Right("0000000000" & ThisCell, 10)
        Else
        End If
    Next ThisCell
    Application.ScreenUpdating = True

    Range("C1:C1500").Select
    Selection.Copy
    Columns("A:A").Select
    Selection.Insert Shift:=xlToRight
    Columns("A:A").EntireColumn.AutoFit
    Columns("A:C").Select
    Application.CutCopyMode = False
    With Selection
        .HorizontalAlignment = xlGeneral
        .VerticalAlignment = xlCenter
        .WrapText = False
        .Orientation = 0
        .AddIndent = False
        .IndentLevel = 0
        .ShrinkToFit = False
        .ReadingOrder = xlContext
        .MergeCells = False
    End With
    With Selection
        .HorizontalAlignment = xlCenter
        .VerticalAlignment = xlCenter
        .WrapText = False
        .Orientation = 0
        .AddIndent = False
        .IndentLevel = 0
        .ShrinkToFit = False
        .ReadingOrder = xlContext
        .MergeCells = False
    End With
    
     Application.ScreenUpdating = False
Set rg = Selection
For Each cel In rg.Cells
    If Len(cel.Text) = 1 Then
        cel.Value = Val(cel.Value)
        cel.NumberFormat = "00"
    End If
Next
    
    

        
    '*****************************
'Determine how many seconds code took to run
  SecondsElapsed = Round(Timer - StartTime, 2)

'Notify user in seconds
  MsgBox "This code ran successfully in " & SecondsElapsed & " seconds", vbInformation


End Sub