I work and deal with weblogic for almost 8 years since version 5. So far I never had to do such thing. Usually performance problems are related to one of these:
Bad application code. Usually Synchronized blocks - fat locks or bad designed DB Queries and memory leaks primary among others.
Poor db performance.
DB Connection leaks.
Network issues(oveloaded router, network cards hardware problems, overloaded load balancers among others).
This I would say cover maybe 90% of the problems I have faced. Taking out the cluster and session replication will make your application less fault tolerant and your production environment harder to administrate. I can´t say it will not work for you but I really NEVER had a problem solved taking this approach.