【MSCE C#】LoadRootModelById加载速度过慢

    public string GetAttachmentPath(string file, string modelName, int referenceIndex)
        {
            string referenceFile = null;
            DgnDocument pDgnDoc = DgnDocument.CreateForLocalFile(file);
            DgnFile pDgn = DgnFile.Create(pDgnDoc, DgnFileOpenMode.ReadWrite).DgnFile;
            StatusInt openForWriteStatus;
            pDgn.LoadDgnFile(out openForWriteStatus);

            if (!pDgn.IsOpen)
                return null;
 
            bool IsFindModel = false;
            foreach (ModelIndex mi in pDgn.GetModelIndexCollection())
            {
                if(modelName == mi.Name)
                    IsFindModel = true;
            }

            if (!IsFindModel)
                return null;

            var dgnModelId = pDgn.FindModelIdByName(modelName);
            DgnModel dgnModel = pDgn.FindLoadedModelById(dgnModelId);
            
            if (dgnModel == null)
            {
                StatusInt errorDetails;
                  dgnModel = pDgn.LoadRootModelById(out errorDetails, dgnModelId, true, true, false);
            }

            var attatches = new List<DgnAttachment>(dgnModel.GetDgnAttachments());

            if (attatches == null || attatches.Count == 0 || referenceIndex < 0 || referenceIndex > attatches.Count - 1)
            {
                referenceFile = null;
            }
            else
            {
                DgnFile abc = attatches[referenceIndex].GetDgnFile();
                if (abc == null)
                    return null;
                referenceFile = attatches[referenceIndex].GetDgnFile().GetDocument().FileName;
            }
            
            StatusInt stat = pDgn.ProcessChanges(DgnSaveReason.FileClose);
            pDgn.Release();

            return referenceFile;
        }

在使用上面函数获取一个外部文件的参考文件路径名时调用LoadRootModelById需要130ms左右,在调用100次时需要十几秒,请问有没有更加快速的获取dgnmodel的方法?