How to speed adding items to a ListView?

I took a look at the source code for the list view and I noticed a few things that may make the performance slow down by the factor of 4 or so that you're seeing:

in ListView.cs, ListViewItemsCollection.AddRange calls ListViewNativeItemCollection.AddRange, which is where I began my audit

ListViewNativeItemCollection.AddRange (from line: 18120) has two passes through the entire collection of values, one to collect all the checked items another to 'restore' them after InsertItems is called (they're both guarded by a check against owner.IsHandleCreated, owner being the ListView) then calls BeginUpdate.

ListView.InsertItems (from line: 12952), first call, has another traverse of the entire list then ArrayList.AddRange is called (probably another pass there) then another pass after that. Leading to

ListView.InsertItems (from line: 12952), second call (via EndUpdate) another pass through where they are added to a HashTable, and a Debug.Assert(!listItemsTable.ContainsKey(ItemId)) will slow it further in debug mode. If the handle isn't created, it adds the items to an ArrayList, listItemsArray but if (IsHandleCreated), then it calls

ListView.InsertItemsNative (from line: 3848) final pass through the list where it is actually added to the native listview. a Debug.Assert(this.Items.Contains(li) will additionally slow down performance in debug mode.

So there are A LOT of extra passes through the entire list of items in the .net control before it ever gets to actually inserting the items into the native listview. Some of the passes are guarded by checks against the Handle being created, so if you can add items before the handle is created, it may save you some time. The OnHandleCreated method takes the listItemsArray and calls InsertItemsNative directly without all the extra fuss.

You can read the ListView code in the reference source yourself and take a look, maybe I missed something.

In the March 2006 issue of MSDN Magazine there was an article called Winning Forms: Practical Tips for Boosting The Performance of Windows Forms Apps.

This article contained tips for improving the performance of ListViews, among other things. It seems to indicate that its faster to add items before the handle is created, but that you will pay a price when the control is rendered. Perhaps applying the rendering optimizations mentioned in the comments and adding the items before the handle is created will get the best of both worlds.

Edit: Tested this hypothesis in a variety of ways, and while adding the items before creating the handle is suuuper fast, it is exponentially slower when it goes to create the handle. I played with trying to trick it to create the handle, then somehow get it to call InsertItemsNative without going through all the extra passes, but alas I've been thwarted. The only thing I could think might be possible, is to create your Win32 ListView in a c++ project, stuff it with items, and use hooking to capture the CreateWindow message sent by the ListView when creating its handle and pass back a reference to the win32 ListView instead of a new window.. but who knows what the side affects there would be... a Win32 guru would need to speak up about that crazy idea :)

I used this code:

ResultsListView.BeginUpdate();
ResultsListView.ListViewItemSorter = null;
ResultsListView.Items.Clear();

//here we add items to listview

//adding item sorter back
ResultsListView.ListViewItemSorter = lvwColumnSorter;


ResultsListView.Sort();
ResultsListView.EndUpdate();

I have set also GenerateMember to false for each column.

Link to custom list view sorter: http://www.codeproject.com/Articles/5332/ListView-Column-Sorter