No worries. You can do a few things here;
1) Use a dedicated server backup interface on a different subnet/VLAN that doesn't pass through the F5 (same or different local switch, doesn't really matter)
2) Use the same server interface but VLAN tagging to a different subnet/VLAN that doesn't pass through the F5 (same or different local switch, doesn't really matter)
3) Use a Performance (Layer4) VS to handle the traffic with minimal overhead (assuming bandwidth completely swamped)
4) If bandwidth is a real issue, do 3) but apply a suitable Rate Class to manage it (assuming this won't delay the backup too much)
Personally in environments I work in 1) is the common approach whatever the infrastructure and regardless of the F5. That or direct SAN attachment. Hope this helps.