BigIP Virtual edition vlan-group tcp retransmissions

Hello,

I've been having serious performance issues with a load balanced environment, using a vlan-group. Machine to machine within the same vlan, traffic is error free. Machine to machine across the vlan-group and we get a massive amount of tcp retransmissions and DUP ACKs. The vlan-group is set for transparent, but we get the same response in our lab when trying translucent or opaque. I'm kinda at a standstill on what to check next. This used to be physical servers with a cisco ACE 4710 bridging vlans and we never had a performance problem. Any help or pointers would be greatly appreciated.

-CN