WebSphere Application Server large virtual memory process size on Red Hat Enterprise Linux 6 performance degradation

UPDATE:
You will get an instant 10% performance boost if you configure MALLOC_ARENA_MAX=1 on Linux RHEL 6 JVMs

See https://bugzilla.linux.ibm.com/show_bug.cgi?id=79624

If after migrating websphere application server from RHEL 5 to RHEL you see a increase in the virtual memory size of your JVM checkout

http://www.quora.com/Why-do-some-applications-use-significantly-more-virtual-memory-on-RHEL-6-compared-to-RHEL-5 
  https://www.ibm.com/developerworks/mydeveloperworks/blogs/kevgrig/entry/linux_glibc_2_10_rhel_6_malloc_may_show_excessive_virtual_memory_usage?lang=en

This manifests itself as a doubling of the resident size of the JVM as compared to its virtual memory size.

This can be fixed by setting environment variable (https://www-304.ibm.com/support/docview.wss?uid=swg21254153),
Name=MALLOC_ARENA_MAX and Value=1