Worksheet Checkboxes if row is not blank

I am working with a very large table with a range of $B$7:$G$16006 (with the headers in row 6) that is updated dynamically through sheet formulas.

My issue is related with inserting a checkbox (Form control type) next to each row in cell $A7 if the formula in column C (second column in my table) does not result in a "" or "0".
The formula I am working with is:

Sub AddCheckBoxToCell(Ref_Cell As Range)
 
  Dim ChkBox As CheckBox
  Dim N As Double
 
    With Ref_Cell.Cells(1, 1)
      RefLeft = .Left
      refTop = .Top
      refHeight = .Height
    End With
 
      Set ChkBox = ActiveSheet.CheckBoxes.Add(10, 10, 15, 12)
      N = (refHeight - ChkBox.Height) / 2#
  
      With ChkBox
        .Caption = ""
        .Top = refTop + N
        .Left = RefLeft
        .OnAction = ""
      End With
 
End Sub
 
Private Sub Worksheet_Activate()
 
Application.Calculation = xlCalculationManual
Application.ScreenUpdating = False
  Dim BoxCol As Variant
  Dim CtrlCol As Variant
  Dim LastRow As Long
  Dim R As Long
  Dim StartRow As Long
 
  For Each c In Sheets("Sheet1").CheckBoxes
    c.Delete
  Next
 
    BoxCol = "A"     'Column where Check Box is inserted
    CtrlCol = "C"    'Column that controls if Check Box is inserted
    StartRow = 7
    LastRow = Cells(Rows.Count, CtrlCol).End(xlUp).Row
   
        For R = StartRow To LastRow
          If Cells(R, CtrlCol) <> 0 Then
            AddCheckBoxToCell Cells(R, BoxCol)
          End If
        Next R
           
End Sub

The problem with this is that 1) this takes forever to execute/freezes excel due to the number of table rows to loop through (16000) and 2) I cannot figure out how to incorporate the "LinkedCell" code needed to insert TRUE/FALSE in to the address cell of each checkbox.

I have also been looking at "Marlett checkboxes" however cannot figure out how to create the code to only add the Marlett feature to a cell in column A if the row/cell in column C is not "" or "0":

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
 
    If Target.Cells.Count > 1 Then Exit Sub
        If Not Intersect(Target, Range("A1:A100")) Is Nothing Then
            Target.Font.Name = "Marlett"
 
                If Target = vbNullString Then
                    Target = "a"
                Else
                    Target = vbNullString
                End If
        End If
End Sub

Suggestion are greatly appreciated, apologies for the long post but I am trying to find the best approach!

Update: went with the Marlett checkboxes, only needed to modify the If statement:

 If Target = vbNullString And Target.Offset(0,2).Value= 0 Then