A workflow is a flow of work carried out by workers, and workflow management is to automate the flow of work. In workflow management, an actual work is carried out based on the workflow, which is called case. In order to effectively meet various requirements, it is necessary to change current workflow dynamically, which is called dynamic workflow change. When the dynamic change is required, there exist cases in the workflow. In order to handle these cases and further to keep the queuing order, the dynamic change takes period of time (called transient time) until the changed workflow becomes steady state again. During the transient time, workers are forced to do irregular work, and therefore it is important to clarify if a change type takes shorter transient time. In this paper, we do the performance evaluation on transient time of dynamic workflow changes. To do so, we first give a definition of transient time, and then propose methods of computing transient time of three change types proposed by Ellis et al. Finally, we do the performance evaluation for 90 dynamic changes by computing the transient times.