This message was posted on behalf of Intel Corporation
Thank you for posting in Wired Communities. . The STP is the protocol configured on the switch to prevent looping in the network. STP has some default timers when adds up will have a total of 30 to 50 seconds, thus when STP is enabled, this additional s of convergence time might adds overhead in network performance. You may also refer to page 52 of our Teaming user guide at https://downloadcenter.intel.com/download/11848?_ga=2.150806198.1472144631.1510894564-1105153325.1509933445
As stated therein "Spanning tree protocol should be disabled on switch ports connected to teamed adapters in order to prevent data loss when the primary adapter is returned to service (failback)."
By the way, may I know what is the motherboard and NIC model. As this is a configuration on the switch, you may contact your switch vendor for further clarification or more information. Thank you.