An application to set aside a writ of execution on the basis of patent defects in the writ itself constitutes a different cause of action from an application to stay execution pending rescission of the underlying judgment, and therefore the doctrine of res judicata does not apply. For purposes of urgency, the relevant triggering event is when the writ is executed and property attached, not when the underlying order was granted. A party is entitled to challenge the regularity of a writ of execution even where a previous application for stay of execution has been dismissed, provided the cause of action is distinct. The balance of convenience favours granting interim relief to prevent irreparable harm where a writ seeks to recover liquidated amounts not clearly evident from the underlying order.