VBA if a row is all blank in a range of columns, highlight the blanks and the headers

[AnnAnn]

Hello,
This code works but takes 11 seconds to run on a 500 row sheet; it's part of a large main macro and I need it to run faster. I've searched Google, YouTube, and other threads on this site but can't find what I need.
Dim lastRow As Long, lastCol As Long, i As Long
Dim col As Variant
Dim headerCell As Range

lastCol = last_col(ws)
lastRow = Last_Row_For_Realsies(ws, lastCol)

Dim checkColumns As Variant
checkColumns = Array("A", "B", "C", "D", "E", "F", "G", "H", "K", "M", "P", "Q", "S", "U", "W", "Y", "AA")

For i = 3 To lastRow
Dim allBlank As Boolean

allBlank = True


For Each col In checkColumns
If ws.Cells(i, col).Value <> "" Then
allBlank = False
Exit For
End If
Next col

If allBlank Then

For Each col In checkColumns
ws.Cells(i, col).Interior.Color = RGB(255, 204, 0)
Set headerCell = ws.Cells(2, col)
headerCell.Interior.Color = RGB(0, 0, 0)
headerCell.Font.Color = RGB(255, 255, 255)
Next col
End If

Next i

 

[Micron]

I don't see where ws was declared where the posted code contains the ws reference.

 

[AnnAnn]

I don't see where ws was declared where the posted code contains the ws reference.

It's declared in the title of the Sub, please see below.
Sub AllBlankPFINs(ws As Worksheet)

When I call it in the main sub, I use:
Call Sub AllBlankPFINs(ws)

All of my other subs work when I use both of these, except when Union or Intersect is in the code.