The default XPath check used by Gatling is based on Jaxen and Xerces. Like most XPath implementations, it loads a DOM tree of the document in memory. This leads to high memory usage which you might want to avoid if you want to use XPath checks throughout your scenarios.
To mitigate this, we wrote this plugin using VTD-XML, an XML parsing library that still loads the XML document in memory; but instead of creating the DOM, it creates an index, leading to big memory savings.
VTD-XML check plugin is available for download here.
The VTD-XML binaries can be downloaded here.
The source is hosted on Github and published under GPLv2.