One of the most common reasons is lack of allocated memory. As more and more users start working with the system memory consumption becomes bigger and bigger. If there is not enough memory allocated to system components every request for memory takes longer and longer to fulfill. Eventually out-of-memory error occurs.
So monitor the memory used up by Aware IM components (Aware IM Server, Tomcat and JBoss) when the slowdown happens. If you find that memory used is close to what you allocated for the component try to increase the memory for this component.
