Prior to SMP 7.1 SP2, we used the following two settings:
MaxConcurrentFastMsgs and MaxConcurrentSlowMsgs
After SMP 7.1 SP2 the following settings were introduced, replacing the two above (those are not longer used and on new SMP 7.1 SP2 installations will not be present the all):
MaxConcurrentFastMsgsThreadPoolSize and MaxConcurrentSlowMsgsThreadPoolSize
However, MaxConcurrentSlowMsgsThreadPoolSize is not used anymore –slow / large message processing is now defaulted to have 1 thread per queue (one for “slow” and one for “large”).
Regarding changing the values for MaxConcurrentFastMsgsThreadPoolSize as we did with MaxConcurrentFastMsgs, there is not a specific reason that we would like to decrease the values, but it should not bring any troubles at all. If we need to change the value as a way to just to avoid deadlocks while processing NSEs, it’s absolutely fine, either decreasing or increasing.
Read more about changes done with the Event Queues post SMP 7.1 SP2 here: DOC5480 "Event Queues in ITMS 7.1 SP2" or https://www-secure.symantec.com/connect/articles/event-queues-itms-71-sp2