XMLReader::expand() expands the current subtree to DOM. SimpleXML is good too. To avoid a warning like "Imported Node must have associated Document" when using simplexml_import_dom(), we can do :<?php // Huge XML compressed file$xml = XMLReader::open('compress.zlib:///path/to/my-data.xml.gz');// Targeting a tiny subtreewhile ($xml->name !== 'my-targeted-element') { $xml->read();}// The trick is here...// Subtree is expanded in an empty document...$dom = $xml->expand(new DOMDocument());// ... which can be imported by SimpleXML$sx = simplexml_import_dom($dom);// We can now process our tiny subtree with SimpleXML $sx