Thierry de Coulon via tde-users wrote:
I usually do this by a right-click on the Desktop, then "log out" and I get a choice of Log out, Shutdown, Restart, Freeze, Suspend, Hibernate, Hybrid hibernate and Cancel, which almost always works (I did not try Freeze, Suspend, Hibernate, Hybrid hibernate on this desktop computer; On laptops Suspend usually works, Hibernate not always).
In the case of OP with poweroff there is a delay, but with shutdown there is no delay, so I suggested to try setting shutdown command instead of poweroff (or may be the script he uses to shut down)