I have a .Net webserivce that accepts XML in string format. XML String sent into the webserivce can represent any Object in the system. I need to check the first node to figure out what object to deserialize the XML string. For this I will have to load the XML into an XMLDocument (Don't want to use RegEx or string compare). I am wondering if there is a way to Deserialize the XMLDocument/XMLNode rather that deserializing the string to save some performance? Is there going to be any performance benefit serializing the XMLNode rather that the string?

Method to Load XMLDocument

public void LoadFromString(String s)
{
    m_XmlDoc = new XmlDocument();
    m_XmlDoc.LoadXml(s);        
}

Thanks