Bridge Zero Copy Transmit

Zero copy transmit mode is effective on large packet sizes. It typically reduces the host CPU overhead by up to 15% when transmitting large packets between a guest network and an external network, without affecting throughput. 

 

 Source: Red Hat - Network Tuning Techniques 

 # /etc/modprobe.d/vhost-net.conf

+ options vhost_net	experimental_zcopytx=1