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Editorial Team
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Asked: 2026-06-03T03:48:09+00:00

I’m running into a problem with the WPF TreeView control. I think I ran

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I’m running into a problem with the WPF TreeView control.
I think I ran into a memory leak issue with this control and also some performance issues.
I’ve prepared a simple demo solution where you can see these problems.
Download link: http://www.custom-projects.com/TreeViewMemoryAndPerformanceIssue.zip

I’m creating the tree based on some domain objects. The objects are wrapped in view models.
The number of levels is not restricted, but currently we have a maximum of 3 levels.

So, each view model can have children.

When you click on the up/down buttons of the UpDown control and don’t release the mouse button you will see, that the update speed of the int value will get slower and slower and the memory consumption constantly rises.

What I’m doing: When you click on the up/down button the value is sent to the view model via data binding. In the setter I’m raising a event. Our application consists of different view models and if someone is changing data in one of them, the others are notified through these DataChanged events.

For simplicity, my demo solutions just consists of the NavigationViewModel. So it listens
for the DataChanged event and if fired, the tree is rendered.

Because we don’t have a list which will always be the same (and just rows are added or removed), I’m not using a ObservableCollection. We always have to regenerate the list based on the objects the user has added/created.

Anyways, I’m adding these view models to a list and raise the NotifyPropertyChanged event
so that WPF updates the tree. Works well but the more the list is updated, the slower the application gets (and memory goes up).

I checked, that the item view models are garbage collected and they are, so I don’t see
something wrong on my side. I also did some performance profiling. It looks, that the
issue is on the WPF side, because my code does not slow down. The Application.Run method
execution time rises… Strange thing.

Does anyone has an idea, why the memory is going up and never gets released and why the
performance starts to decrease the more often the TreeView updates itself?

I would appreciate any help or comment on this issue.

Thanks,
Christian

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1 Answer

  1. Editorial Team

    I profiled your test application using ANTS Memory Profiler and you can see that your classes ‘NavigationItemBaseViewModel’ and the array “NavigationItemBaseViewModel[]” are still held in memory by references, and this is getting worse with each increment.

    If you slowly increment and allow the update to happen, then the references are broken and objects disposed. All good.
    However, if you increment fast/continuously then you see that your references are not broken, thus the arrays are kept in memory.

    The increments get slower each time because your application is having to update a lot of these view models, at increment #58 I had 172 arrays holding between them 517 NavigationItemBaseViewModel’s.
    Where with “normal” functionality you only have 4 arrays and 13 NavigationItemBaseViewModel’s.

    Hope that helps, I would recommend you profile your memory if you cannot figure out your logic where new are creating new arrays. Typically it is best to reuse arrays.

    Profiler I used is here: http://www.red-gate.com/products/dotnet-development/ants-memory-profiler/index2

    Hope that helps.

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