1) In `JAXPXPathEvaluator` the XPath expression should be compiled.

https://github.com/apache/activemq-artemis/blob/5f7faa47ccf30c31cce217c7b6dcf91563eeab67/artemis-selector/src/main/java/org/apache/activemq/artemis/selector/filter/JAXPXPathEvaluator.java#L57-L63

2) Instead dumping the message body as String, at least for big (not large) messages, a streaming base approach should be used (XLST 3 supports streaming AFAIK)