Forum Discussion
have a look at this article about the different profiles (TCP / FastL4):
http://support.f5.com/kb/en-us/products/big-ip_ltm/manuals/product/ltm-concepts-11-1-0/ltm_protocol_profiles.html
it is a shame that you can either disable or enable Extensions for High Performance (RFC 1323) as a whole and not just turn off Time Stamps there as the window scaling can be quite useful. might be related that if you implement RFC 1323 you do it all or nothing. the effect depends on what the clients and / or servers support and use, it might be they hardly use this at all currenly.
personally i would raise a ticket with F5 support and ask them to check this for you and perhaps come with a suggestion to make you PCI compliant without loosing any performance. probably not the first time they are asked this question.
btw F5 themselves don't really see this as an issue (but that probably doesn't help much against the PCI auditor :) )
http://support.f5.com/kb/en-us/solutions/public/8000/000/sol8072.html