图片框中的LoadAsync映像的内存不足异常

Question

我在运行时将图片加载到图片框中，当有20-30张图片但图片超过50张时，它将正常工作，然后PictureBox LoadAsync随机方法开始发出内存不足异常。

ArrayList imageList = ExtractImagesFromPDF(schedule_pdf);
foreach (var item in imageList)
{
    Imagethumnail picbox = new Imagethumnail();

    picbox.img.LoadAsync(
        Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData)
        + "\\" + Convert.ToString(item)
    );

    picbox.img_name.Text = Convert.ToString(item);
    picbox.img.SizeMode = PictureBoxSizeMode.StretchImage;
    picbox.Location = new Point(x, y);

    picbox.Height = 400;
    picbox.Width = 250;
    x += picbox.Width + 10;
    maxheight = Math.Max(picbox.Height, maxheight);
    if (x > this.ClientSize.Width - 100)
    {
        x = 20;
        y += maxheight + 10;
    }
    this.pnl_imags.Controls.Add(picbox);
}