The XMLmini implementation now switches between a LibXML or REXML implementation, depending on weather the LibXML library is available. As the implementation of the XMLmini is now separated out, it is very easy to implement Nokogiri or JREXML. The speed increase is quite stunning (in my tests up to 10 times as fast, probably more for larger XML files).
It falls back to the old ruby implementation (REXML) if no other parsers are available. http://rails.lighthouseapp.com/projects/8994/tickets/2084-alternative-xml-parsers-support-in-activesupport-for-activeresource
