大文件预览，容易卡死

文件大概500页面，就这样，嵌入在我们的业务里面，就卡着了鼠标不能点击

instance = WebOfficeSDK.init({
  mount: this.$refs.wps,
  officeType: WebOfficeSDK.OfficeType.Writer,
  appId: window.wpsAppId,
  fileId: this.fileId,
  token: token,
  mode: 'simple',
});