Almost every SOA developer/administrator hits the issue of performance while doing SOA implementation. And 95 out of 100 times one decides to play with JVM parameters.
It typically looks something like:
-Xmx4096M -Xms4096M -Xmn3072M -XX:PermSize=1024M -XX:MaxPermSize=1024M -Xloggc:/tmp/verbosegc.txt -XX:+PrintGCTimeStamps -XX:+PrintGCDetailsJconsole can used to monitor and identify bottlenecks for SOA/Weblogic servers. More info can be found here.
Found this excellent blog by Francis that explains How to Set JVM Parameters in Oracle SOA 11G?
More info on JVM tuning that I found really informative here.
Another great blog on performance tuning by Ahmed Aboulnaga.