Very Slow Application performance behind F5

Just a guess, but does your web server have redundant nics? I ran into a situation where load balanced servers with teamed nics were load balancing transmitted traffic. This caused problems with the v 9.4.6 LTM where I was running a FastL4 profile and doing SSL termination, since it was tracking the connection based on source mac which was changing. Once we changed the teamed nic config to only use the secondary nic in the event of failure on the first, it worked fine.