Host uses Linux bridge, VM Guest uses Virtio NIC model. I enabled the iperf3 server on the Host and then tested on the VM Guest,Then I get the following result:
[ 5] 0.00-1.00 sec 2.08 GBytes 17.9 Gbits/sec 0 2.53 MBytes
[ 5] 1.00-2.00 sec 2.91 GBytes 25.0 Gbits/sec...