使用文件制作缩略图

我想知道使用文件为现有图像制作缩略图而不是将其保存到磁盘中是否有任何缺点。是否有与此相关的内存问题?
我的代码:

// thumbnails.aspx
protected void Page_Load(object sender, EventArgs e)
{
    string file = Request.QueryString["i"];
    if (file == null)
        return;
    if (!IsFileExists(file))
        return;
    Thumb(file);
  }
public void Thumb(string file) 
{
    System.Drawing.Image image = System.Drawing.Image.FromFile(Server.MapPath(file));
    System.Drawing.Image thumbnailImage = image.GetThumbnailImage(70, 70, new System.Drawing.Image.GetThumbnailImageAbort(ThumbnailCallback), IntPtr.Zero);
    System.IO.MemoryStream imageStream = new System.IO.MemoryStream();
    thumbnailImage.Save(imageStream, System.Drawing.Imaging.ImageFormat.Jpeg);
    byte[] imageContent = new Byte[imageStream.Length];
    imageStream.Position = 0;
    imageStream.Read(imageContent, 0, (int)imageStream.Length);
    Response.ContentType = "image/jpeg";
    Response.BinaryWrite(imageContent);
}