Demantra 12.2.5.1 Unable to save data in Workskeets in WebLogic 12c with > 5 users, Tomcat and WebLo

I am not sure how many of you have seen this, but Weblogic 12c is supposed to be certified with Demantra 12.2.5, and when we deploy Demantra 12.2.5.1 with the latest mandatory patches to Weblogic 12.1.3 or 12.2.1, we find worksheets hang saving data when multiple users are accessing Demantra concurrently.  At one client, we could make it work by setting the -Xms and -Xmx to 16GB and bouncing Weblogic nightly.  If we start Tomcat or deploy to Weblogic 10.3.6, users can save data fine with 3 or 4GB of heapsize (in WLS 11g).  Is there some other nondefault setting