Strange thing happened recently. A WCM system (6.1x) was being used (connect servlet access) by an application. We noticed that every time the application made a call for an item of content, a new Portal session was created. This had seriously bad consequences for the portal.
The solution was very easy since WAS can be tuned to run off (or on) anonymous sessions.
1. Open WAS admin console
2. Goto "Resources > Resource Environment Providers > WP_NavigatorService > Custom properties"
3. Add a new property named public.session with a value of false.
For related information take a look at:
Seems to be an issue with the previous version (5.1) too since I found this: