the cmf sandbox is using sqlite only because this is the most simple thing to setup. for a production system with jackalope-doctrine-dbal, i would rather use mysql or postgres.
if you want optimal performance, your best option is jackalope-jackrabbit and installing the jackrabbit java server. for a production environment, you should install jackrabbit with tomcat. there is a tutorial in the jackalope wiki: https://github.com/jackalope/jackalope/wiki/Running-jackrabbit-in-tomcat-with-mysql