Clearing the memory or files after opening using a macro - excel

Question

I have a VBA macro that open files in a folder, download data from an add-in, save and close.
This runs fine, but after 10 or 15 files, it gets quite slow. I think it is because Excel still keep previously opened files in the memory. I knew this because I saw the already-opened-and-closed files on the left panel as in the photo below. (the photo is to show where the panel is, I know there is only one file opened with the sheets, but you know what I mean).
My question is: is there a line of code that refresh or clear this temporary memory?
Here is my code:
'PURPOSE: To loop through all Excel files in a user specified folder and perform a set task on them
Dim wb As Workbook
Dim myPath As String
Dim myFile As String
Dim myExtension As String
Dim filename As String
Dim path_to_save As String
Dim FldrPicker As FileDialog
Dim w As Long
Dim StartTime As Double
Dim SecondsElapsed As Double
Dim oFile As Object
Dim oFSO As Object
Dim oFolder As Object
Dim oFiles As Object
Application.ScreenUpdating = False
StartTime = Timer
'Retrieve Target Folder Path From User
Set FldrPicker = Application.FileDialog(msoFileDialogFolderPicker)
With FldrPicker
.Title = "Select A Target Folder"
.AllowMultiSelect = False
If .Show <> -1 Then GoTo NextCode
myPath = .SelectedItems(1) & "\"
End With
'In Case of Cancel
NextCode:
myPath = myPath
If myPath = "" Then GoTo ResetSettings
'Assign the folder to oFSO
Set oFSO = CreateObject("Scripting.FileSystemObject")
Set oFolder = oFSO.GetFolder(myPath)
Set oFiles = oFolder.Files
If oFiles.Count = 0 Then GoTo ResetSettings
For Each oFile In oFolder.Files
'Set variable equal to opened workbook
myFile = oFile.Name
Set wb = Workbooks.Open(filename:=myPath & myFile)
Set cmd = Application.CommandBars("Cell").Controls("Refresh All")
cmd.Execute
DoEvents
'Ensure Workbook has opened before moving on to next line of code
wb.Close savechanges:=True
'Ensure Workbook has closed before moving on to next line of code
DoEvents
Next 'oFile
SecondsElapsed = Timer - StartTime
MsgBox "This code ran successfully in " & SecondsElapsed
Set oFile = Nothing
Set oFolder = Nothing
Set oFSO = Nothing
ResetSettings:
'Reset Macro Optimization Settings
Application.ScreenUpdating = True
End Sub

Answer 1

What about add:
set cmd = nothing
before
wb.Close savechanges:=True

Answer 2

There is a known issue in Excel with closed Workbooks leaving data in Memory, which can only be cleared by closing and reopening Excel.
The below code uses a late-bound second instance of the Excel application, in an attempt to alleviate this issue; the second instance will be closed and reopened periodically (currently set to every 5 files).
Sub SomeName()
'PURPOSE: To loop through all Excel files in a user specified folder and perform a set task on them
Dim wb As Workbook
Dim myPath As String
Dim myFile As String
Dim myExtension As String
Dim filename As String
Dim path_to_save As String
Dim FldrPicker As FileDialog
Dim w As Long
Dim StartTime As Double
Dim SecondsElapsed As Double
Dim oFile As Object
Dim oFSO As Object
Dim oFolder As Object
Dim oFiles As Object
'NEW CODE
Dim appXL AS Object, counterFiles AS Long
counterFiles = 0
Application.ScreenUpdating = False
StartTime = Timer
'Retrieve Target Folder Path From User
Set FldrPicker = Application.FileDialog(msoFileDialogFolderPicker)
With FldrPicker
.Title = "Select A Target Folder"
.AllowMultiSelect = False
If .Show <> -1 Then GoTo NextCode
myPath = .SelectedItems(1) & "\"
End With
'In Case of Cancel
NextCode:
myPath = myPath
If myPath = "" Then GoTo ResetSettings
'Assign the folder to oFSO
Set oFSO = CreateObject("Scripting.FileSystemObject")
Set oFolder = oFSO.GetFolder(myPath)
Set oFiles = oFolder.Files
If oFiles.Count = 0 Then GoTo ResetSettings
For Each oFile In oFolder.Files
'NEW CODE
If appXL Is Nothing Then Set appNewExcel = CreateObject("Excel.Application")
DoEvents
'Set variable equal to opened workbook
myFile = oFile.Name
Set wb = appNewExcel.Workbooks.Open(filename:=myPath & myFile)
'Update / Refresh workbook
wb.RefreshAll
appNewExcel.CalculateFullRebuild
DoEvents
'Ensure Workbook has opened before moving on to next line of code
wb.Save
DoEvents
wb.Close savechanges:=True
'Ensure Workbook has closed before moving on to next line of code
'NEW CODE
Set wb = Nothing
counterFiles = counterFiles+1
If counterFiles mod 5 = 0 Then
appNewExcel.Quit
Set appNewExcel = Nothing
End If
DoEvents
Next 'oFile
SecondsElapsed = Timer - StartTime
MsgBox "This code ran successfully in " & SecondsElapsed
Set oFile = Nothing
Set oFolder = Nothing
Set oFSO = Nothing
ResetSettings:
'Reset Macro Optimization Settings
Application.ScreenUpdating = True
End Sub