SAP Performance Question

Currently, we have an integration where SAP will send 3000+ IDoc (small custom IDoc with size < 1K).

We have a performance issue where the initial 1000+ IDoc are processed successfully and quickly, however, as more IDocs are sending, the response time start degrading (to the point of over 60 seconds, where SAP ALE/RFC will time out)

We have try increasing the number of SAP Listeners Thread (to 10 and 20), but, based on webMethods, it never uses more than 7 Listeners)

We are on I.S. 6.1 SP1/FP2 with SAP Adapter 4.6 (with all fixes applied).

Any ideas/comments ?? Network Issues ?? SAP Gateway Problems ?? SAP Configuration…We are running out of idea to try (we even put network sniffer on, but to no avail)

Is it possible to add logging statements or timers to each major “chunk” of processing to determine where the slowdown is occuring?

For example, if you have to perform four tasks to process each IDoc, does one of those steps begin to take progressively longer? What happens to the number of available threads in the service pool during the slowdown period? Are there always plenty are does the process become “starved” for available threads in the server thread pool? If so, you might be able to improve performance by increasing the number of threads in the server thread pool, but that might move the processing bottleneck futher downstream as well.