Performance issues in Multithreaded environment

Have you measured wall clock time or processing time for the rules service? A 5 to 40 seconds increase suggests latency/context switching in your service invocation... 

Does your rule service communicate with other resources as part of the rules processing? I.e. is your rule service a standalone component, or does it depend on/communicate with a database/web service/some other external component?

How many agents are configured/how do you deploy your rule services? 

I don't think there is any magic to making Blaze Advisor perform well in a multi threaded environment, other than the same principles you would use for other components. To reduce contention is probably the most important one. Also, one rule of thumb for non-ejb, asynchronous, non-latency services is that the number of configured rule agents should equal (number of CPUs or cores) + 2.

Regards, 

Jostein