Here is a code I tried to open a workbook and got the data:
Sub Open_Large_WB_ReadOnly()
Dim WB As Workbook
Dim WBdir As String
Dim Start As Long
Start = Timer
WBdir = "C:... some very large workbook ... .xlsx"
Set WB = Workbooks.Open(WBdir)
Debug.Print WB.Sheets(1).Range("A1").Value
WB.Close (False)
Debug.Print " Regular " & Format(Timer - Start, "0.000")
End Sub
Timer total = Regular 38.066 -> 38 seconds is a long time.