Form Dispose Very Slow...about 10 seconds

A combox can take any object as its item. I just tested with simple strings. Up to 8000 loading goes ok (slows down a bit) from 16000 items I had some notable delay. Closing the form went quick in all situations.

What I'm trying to say here is that your problem lies somewhere else then in the dropdown box. Though it is not a good idea to put so many items in a dropdown box, it is not impossible, nor should it yield too much performance degradation.

If you place objects in your combobox, the combobox will try to dispose of them before removing them. If you do no use a string-version of your objects, this process may cost a significant overhead. The solution is to convert your objects to strings before adding them to the combobox.

-- Abel --

PS: if you remove or add the items manually, try to use this.SuspendLayout before and this.PeformLayout after, if the amount of items to add or remove it significant.

mastoo's suggestion to use a code profiler is of course an excellent idea, it should pinpoint the problem more easily.

I'm a fan of the ants profiler from red-gate.com

I am downloading a test version of the Ants profiler now.. The loading of the Combobox is ok..it's bind to a TableAdapter in my DataSet but when the form close is called it's very slow

>  but when the form close is called it's very slow

which can be the disposing of the object in the table or combobox, whichever comes first. Some code is running in either Dispose events, Close or Unload events which is slowing you down. It is not necessary code that you wrote.

I'd be interested to see what the profiler comes up with.

Hi guys

Maybe I should have mentioned that I am using Telerik controls on my form as well...
I have tried to create a new for with only the ComboBox....and ehen I fill it with data there is no problem but when I close the form it is slow. Then I changed to Windows combobox....no problem..the form closes in 1-2 sec. I am attaching a screen shot of the performance report. I have now send a supprt ticket to Telerik to get some clarity why the behaviour is this like this. I will get back to you regarding that.  

Please, if you want some more information just ask.

Hi guys

Telerik has finally come up with a solution for the problem, for the time being at least. They could not solve this problem without a workaround, but it did solve the problem. Now the form closes in a couple of sec (a bit slower then winforms) but it's acceptable.

Here is the answer I got from them:

Thank you for your sample project.

I was able to reproduce the described behavior. Indeed, we have an issue in the disposing logic of RadComboBox databinding. We will address the issue in one of our next releases, but currently I cannot provide you with a specific time-frame.

Until the issue is addressed, you can set the DataSource property of the RadComboBox to null. This will avoid the execution of the code that causes the problem and your form/dock window will be closed almost immediatelly. I am attaching a modified version of your project that behaves well on my side.  

No points for suggesting the profiler that shows the Telerik controls as the problem?

Hi guys

I'm sorry if that is wrong but he actually wrote the correct suggestion to the problem:
Does the Telerik DropDown allow a RemoveAll or can you set the DataSource to nothing to make it empty? You could do that before the dispose occurs (in form Unload event). Not sure it will help, just a few thoughts.

is that wrong??

No, that's not wrong, but in complex questions it has become customary to award some points to the other participating experts that helped leading you to a solution (you can award multiple experts). Also, others cannot view the grading remarks, which is a missing feature of EE and raises questions with others as to why a question is closed the way it is.

I won't object to another disposition of this question, if you choose to change your opinion and award some others as well, which you can do by clicking Request Attention and asking for reopening.

PS: glad you found a solution though and that the DataSource to Nothing tip worked.

Hi guys

I understand the issue :-) and I am more then happy to award you both. I am so impressed by all you guys who give time and afford to help in our hour of need. You are unevaluated resource for Us, the less knowledgeable :-) I will now request attention so you can share the points.

Tanks again