XML Parsing

Hello,

I need a fast xml parser, that saves the data in memory after the first read, and lets read and update the data.

the operation of searching a child element by name is a very common operation and I need it to be fast (in microsoft DOM implementation this operation is called SelectSingleNode(NodeName))

which parser should I use I want it to be fast, I don't need any more features (like schema validation or XSL transforamation). I also want my parser to use small amount of memory.

thanks.