Hi Sebastien,
It looks like you might be experiencing https://jira.jboss.org/browse/JBREM-1005 "Prevent build up of cancelled TimerTasks in bisocket transport". JBREM-1005 was fixed in Remoting release 2.2.2.SP9, but AS 4.2.2 ships with release 2.2.2.SP1. Try upgrading.
-Ron