The memory in Java application is automatically taken care of by the garbage collect. If it is busy, it usually will not free the momory until it has to free. By default, the JRE in Event Viewer is configured to be able to use up to 128MB memory. So, when this Java application is busy doing its work such as refreshing the window, loading lots of data into Alarm Detail window etc, it will use the available system memory as much as it can until reach to 128MB threshold or no more memory left for it. Then the garbage collect will take effect immediately to free some of the memory which is needed for next action, but those memory may be immediately used by the next action. So you see the memory used in javaw.exe is constantly big.
The machine should have 128MB memory is the minimum requirement. It is better to have 256MB if you have lots of alarms and need to view them constantly. Besides, if you minimize all the GUI windows in Event View, the garbage collect will immediately free the unused memory. You will see the memory dropped down immediately.