Speeding Up VBA Code for If Then Statement with Formula

I currently have two if then VBA codes, that are running extremely slow for my large data set and am looking for ways to optimize and speed them up.

The first formula is looking in a range of cells in column J that have a value in column A, and if they are blank in J then entering in a formula that contains a user defined function.

The second code is looking to see if any of the values in column J end in a , and if they do then remove that comma. Any help would be greatly appreciated!

Sub FillEmpty()
    Dim r As Range, LastRow As Long
    LastRow = Cells(Rows.Count, 1).End(xlUp).row
    For Each r In Range("J2:J" & LastRow)
        If r.Text = "" Then r.FormulaR1C1 = _
           "=IFERROR((IF(LEFT(RC[-9],6)=""master"", get_areas(RC[-7]), """")),"""")"
    Next r
End Sub

Sub NoComma()
    Dim c As Range
    For Each c In Range("J:J")
        With c
            If Right(.Value, 1) = "," Then .Value = Left(.Value, Len(.Value) - 1)
        End With
    Next c
End Sub