If you suspect that Orbeon Forms is running out of memory, add the following to your JVM options:
-verbosegc -XX:+PrintGCDateStamps -XX:+PrintGCTimeStamps -XX:+PrintGCDetails
This will output GC information to the Tomcat logs. The next time Orbeon Forms locks or gets slow, check the GC information in the servlet container logs. This might indicate whether Orbeon Forms blocks because of an actual memory issue or not.
If you suspect that Orbeon Forms is encountering a deadlock, obtain a JVM thread dump. The easiest is to use the
kill command on Linux/Unix. See for example How do I generate a Java thread dump on Linux/Unix?.