C＃.net将usercontrol添加到面板非常慢

Question

我正在编写一个简单的电子邮件客户端，我有一个带有2个标签和2个面板和1个图片框的用户控件。但是创建这些用户控件并将其添加到flowlayoutpanel非常慢。例如，创建和添加20个这样的用户控件到面板需要大约10秒！我需要更快地完成这个过程。任何帮助表示赞赏。这是我的代码：

    MessagesListPanel.SuspendLayout();

MessagesListPanel.Controls.Clear();

foreach (ImapX.Message message in MessagesLibrary.GetMessageList())
{
    EmailListItem NewEmail = new EmailListItem(MessagesListPanel,
        message.UId,
        !message.Seen,
        message.Attachments.Count() > 0,
        message.From.DisplayName == null ? message.From.Address : message.From.DisplayName,
        message.Subject == null ? "(No Subject)" : message.Subject,
        message.UId == LastSelectedID);

    NewEmail.Click += EmailItemClick;
    NewEmail.FromLabel.Click += EmailItemClick;
    NewEmail.SubjectLabel.Click += EmailItemClick;
    NewEmail.AttachmentIcon.Click += EmailItemClick;

    MessagesListPanel.Controls.Add(NewEmail);
}

MessagesListPanel.ResumeLayout();

EmailListItem的构造函数：

public EmailListItem(FlowLayoutPanel MPanel, long uid, bool IsUnread, bool HasAttachments, string From, string Subject, bool Selected)
    {
        InitializeComponent();

        MessagesPanel = MPanel;
        UID = uid;

        if (IsUnread)
        {
            FromLabel.Font = new Font(FromLabel.Font, FontStyle.Bold);
            SubjectLabel.Font = new Font(SubjectLabel.Font, FontStyle.Bold);
        }

        if (HasAttachments)
            AttachmentIcon.Show();

        FromLabel.Text = From;
        SubjectLabel.Text = Subject;

        if (Selected)
            SelectMessage();
    }

public void SelectMessage()
    {
        Selected = true;

        this.BackColor = Color.FromArgb(85, 85, 88);
    }

    public void UnSelectMessage()
    {
        Selected = false;

        this.BackColor = Color.FromArgb(65, 65, 68);
    }