I have a large (35,000+ members) collection in memory which I need to display in a combobox. When I set the ultracombo datasource to this collection during the form_load event, the form becomes unresponsive (all white and unable to move) for about 1.5 seconds. The collection is a very simple one containing only an integer and a string with the string being the displayvalue.
I don't have this problem using the standard combobox control. When I step through the code, there is no delay at all during this assignment, but every time it runs normally I see the problem.
I am using VB2008 and version 8.3.
The delay is probably caused by the Combo building the BinarySearch list. Check out the DropDownSearchMethod property. By default, it's set to do Binary searching. This means there will be an initial delay when the list is built the first time, but it gives much faster search performance for users. If you set this to Linear, it will remove the initial delay, but the control will have to do a linear search down the list whenever the user types into the combo, so it gives slower overall performance at run-time.