When customer runs a load test using Rational Load tester from IBM they are not seeing metrics related to their test.
This is particularly noticeable for SSL load tests.
There is a bug in IBM's product that causes the client to send SSL packets to FxM that are Invalid. You can see the packets in the tcpdump when looking in WireShark they will have the message "Ignored Unknown Record" in the Info column of WireShark.
When FxM sees these packets it continues to hold the session open in memory to try and collect any new packets that can be read, but in the case of the IBM product it just sends more invalid packets that eventually use up all the memory on the system. The IBM load testing software effectively acts as a Denial Of Service (DOS) attack.
Don't use the IBM load testing software to generate load on systems that are monitored by FxM.