What is the test for dismissing a motion for delay?

The principle to be applied on a motion to dismiss for delay is that the action should not be dismissed unless (1) the default is intentional and contumelious, or (2) the plaintiff or his or her lawyers are responsible for the inexcusable delay that gives rise to a substantial risk that a fair trial might not now be possible. (Armstrong v. McCall, [2006] O.J. No. 2055, 2006 CanLII 17248, at paras. 11-12 (O.C.A.))

It has been held that any delay in the prosecution of an action requires an explanation. In the absence of an explanation by the plaintiff, the presumption is that the delay was intentional. (Berg v. Robbins, 2009 CarswellOnt 8705, 266 O.A.C. 200 (Div.Ct.))