Nimbostratus
CirrusFor a rough situation like this where the team is having issue progressing forward with an issue I would copy the virtual server and begin to peel unnecessary features from this newly created test virtual server until I could identify the problem.
If even a bare bones profile fails to resolve the issue, play around with some of the different tcp profiles and virtual server types until resolution is found. Feel free to post the list ltm virtual vs_name all-properties and it's associated profiles for suggestions. I'd also look for interface statistics of interest under the host and tmsh panes of glass that could perhaps give insight on the retransmissions.
Good luck and let us know.