 <p>I personally verified that for domain classes there is a big hit in terms of performances.</p> <p>While trying to solve a performance issue, I found this blog entry <a href="http://blog.oio.de/2010/08/05/updated-grails-domain-class-creation-performance-avoid-named-parameters-in-loops-with-many-iterations/" rel="nofollow">Grails Domain Class Creation Performance</a>, changed from map style constructor invocation and gained a factor on ten when creating a lot of new instances (not to be persisted BTW). </p> <p>I'm using grails 2.01, so the problem (?) is still there.</p>