You don't need the Excel object library reference. This is fast if Excel is already open. Extracting the cell without opening Excel is a challenge without seeing the worksheet.

Sub Macro1()
Dim xlApp As Object
Dim xlWB As Object
Dim bXL As Boolean, bWB As Boolean
Dim sText As String
Const sPath As String = "C:\"
Const sWB As String = "myfile.xls"
    On Error Resume Next
    Set xlApp = GetObject(, "Excel.Application")
    If Err <> 0 Then
        Set xlApp = CreateObject("Excel.Application")
        bXL = True
    End If
    On Error GoTo 0
    xlApp.Visible = True
    For Each xlWB In xlApp.workbooks
        If xlWB.Name = sWB Then
            bWB = True
            Exit For
        End If
    Next xlWB
    If bWB = False Then
        Set xlWB = xlApp.workbooks.Open(sPath & sWB)
    End If
    sText = xlWB.sheets(1).Range("D4")
    Debug.Print  sText 'do something with sText
    xlWB.Close 0
    If bXL = True Then xlApp.Quit
    Set xlWB = Nothing
    Set xlApp = Nothing
End Sub