Xml select查询xpath很慢

My XML structure:

我的XML结构:

<Items>
  <Item>
    <guid>FC550573-7171-997F-752D-8D65590CBFD6</guid>
    <Objects>
       <Object>
         <type>0</type>
         <guid>E10D9DA9-2C8D-8024-2F07-DF21395811BF</guid>
       </Object>
       <Object>
         <type>0</type>
         <guid>D8338400-35C7-781E-A039-C0FDDF80714A</guid>
       </Object>
    </Objects>
  </Item>
</Items>
<Items>
  <Item>