使用 ListBox 显示/绘制对话速度缓慢？

我的应用程序使用实体框架来提取一小部分结果...它需要大约 3 秒才能完成？为什么会这样？

Start.cs

...
private void projectToolStripMenuItem_Click(object sender, System.EventArgs e)
{
    NewProject newProjectForm = new NewProject();
    newProjectForm.ShowDialog(); // It seems to take about 3 or 4 seconds to actually get to this :S
}
...

新项目.cs

public partial class NewProject : Form
{
    private EFProjectTypeRepository projectTypeRepository;

    public NewProject()
    {
        projectTypeRepository = new EFProjectTypeRepository();

        InitializeComponent();
        ListBoxProjectTypes();
    }

    public void ListBoxProjectTypes()
    {    
        DateTime then = DateTime.Now;

        // PreLoadedResources.projectTypes is a preloaded resource which takes split seconds to load.

        ListBoxProjectType.Items.AddRange(PreLoadedResources.projectTypes.Select(item => (object)item.Title).ToArray()); // If I comment this line out, the dialogue is almost instant @ timeTaken  {00:00:00.0010019}

        DateTime now = DateTime.Now;
        TimeSpan timeTaken = now.Subtract(then); 
    }
}

:

timeTaken   {00:00:02.4261369}  System.TimeSpan

当我第二次播放对话时，一切都是即时的！

到目前为止，我的列表框显示 1 项，哈哈。

Notes:

public static class PreLoadedResources
{
    public static IEnumerable<ProjectType> projectTypes;
}

The ListBox每次添加项目时都必须重新绘制。您可以使用 Dmitry 的方法AddRange()，或者你可以用以下方式包裹你的循环BeginUpdate()/EndUpdate() calls.

ListBoxProjectType.BeginUpdate();

foreach( var projectType in projectTypes )
{
    ListBoxProjectType.Items.Add(projectType.Title);
}

ListBoxProjectType.EndUpdate();