This [Tree-based] type of parser is a better option for smaller XML documents, but not for large XML document as it causes major performance issues. - http://www.w3schools.com/php/php_xml_parsers.asp
My question is, when is an XML file considered large? At how many lines/kB/nodes?
Or better, at what XML size should I switch to event-based XML (since I'm using SimpleXML, tree-based, right now)?