Painfully slow "Validating GWT components"

Not sure that GWT plugin is responsible for that.
On project clean validation starts, and it takes more than a minute per validation of each hundred java/ui.xml files in my project on very high end desktop PC. If plugin is responsible for that, then may be it's good idea to check MD5 hash of files before validating them (may be they are not changed since previous validation). Also I don't see any high CPU loading, so this validation process probably could be multithreaded somehow.