Performance of IntelliPrompt.MemberList.Show

How are you adding to them to the MemberList? If you add them one-by-one, that would result in poor performance. If you add all the items at the same time from an array, that works much better. If you're not using that approach, give it a shot and see how it works out.

Another option would be to cache all your constants. You can generate an array holding all the MemberList items for the constants in Excel, PowerPoint, and Word. When you need to show them in a member list, just add the array to the list.

Yes, Boyd said it correctly. Since adding member list items is adding them directly to a ListBox, each time you add an item you are forcing a layout. Therefore, it's best to build up an array of items on your own, then add them all at once with AddRange to achieve maximum performance.

Also, sorting might be causing some slowdown with that many items but it is necessary for the keyboard to pick up the proper items as you type. Alternatively you could probably pre-sort the items and turn off sorting on the member list itself.

Thanks for your response!
You are right. I has test my code: it spends 0.3 second to show and spends 4 seconds to insert item.
I will improve the method to insert item.
Really really thanks. :)