Recursive search for all folders and subfolders in system - vb.net

Question

I wrote a Windows Forms script that searched for all non-hidden and non-readonly folders in my system. But the script itself, when run initially, runs for like 5 minutes. Subsequent opens take much less time. I was wondering if there is a logical error to it, so as to why its running so very slow.
Private Function FindSubFolders(ByVal dir As DirectoryInfo, ByVal node As TreeNode) As TreeNode
Dim subnode As New TreeNode
For Each folder As DirectoryInfo In dir.GetDirectories()
If (folder.Attributes And FileAttributes.Hidden) <> FileAttributes.Hidden Then
subnode = node.Nodes.Add(folder.FullName, folder.Name)
subnode = FindSubFolders(folder, subnode)
End If
Next
Return subnode
End Function
Private Sub SetFolders_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
'Is it possible to load this on 1st (initial) form load???
Try
Dim node As TreeNode
If TreeView1.Nodes.Count < 1 Then
For Each drive As String In Directory.GetLogicalDrives
Directory.GetLogicalDrives()
Dim folders As DirectoryInfo = New DirectoryInfo(drive)
If (folders.Attributes And FileAttributes.ReadOnly) <> FileAttributes.ReadOnly Then
node = TreeView1.Nodes.Add(drive, drive)
Try
node = FindSubFolders(folders, node)
Catch ex As Exception
Console.WriteLine(ex.Message)
Continue For
End Try
End If
Next
End If
If Not IsNothing(My.Settings.Folders) Then
If ListBox1.Items.Count < 1 Then
For Each col As String In My.Settings.Folders
ListBox1.Items.Add(col)
Next
End If
Else
My.Settings.Folders = New StringCollection
End If
Catch ex As Exception
Logs.Add("04", ex.Message)
End Try
Logs.Add("01", "Loaded.")
End Sub
Thanks for the help! :)

Answer 1

Here are a few tips:
One thing you can do to speed things up is to make sure the TreeView-control does not have to repaint itself every time you add an item to it.
Before adding any item, run Treeview1.BeginUpdate and after you have added all items run Treeview1.EndUpdate
If possible, get the directories as an array, and use the node.addrange to add a whole range of directiryes at once.
From MSDN:
To maintain performance while items
are added one at a time to the
TreeView, call the BeginUpdate method.
The BeginUpdate method prevents the
control from painting until the
EndUpdate method is called. The
preferred way to add items to a tree
view control is to use the AddRange
method to add an array of tree node
items to a tree view. However, if you
want to add items one at a time, use
the BeginUpdate method to prevent the
TreeView control from painting during
the add operations. To allow the
control to resume painting, call the
EndUpdate method when all the tree
nodes have been added to the tree
view.
Check out this question for a (maybe) more easy way to fetch the subfolders:
Get all folder / directories list in VB.net