Changing all comments' size in range to autosize
as I research more and tried different ways, I have found that I can use the application.screenupdating way to make my whole program run faster and since this question have been unanswered for quite awhile, I will mark this as my answer once a week has past since I asked this question. however I will still be checking to see if there is any better answers posted here till then. Thank you all!

Sub AutoSizeComments()
    Dim c as range, ws as worksheet

    Application.ScreenUpdating = False
    Set ws = ActiveSheet
    'Loop through each comment on worksheet
    For Each c In ws.Cells.SpecialCells(xlCellTypeComments)
        c.Comment.Shape.TextFrame.AutoSize = True
    Next c
    Application.ScreenUpdating = True
End Sub