# 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](https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html-single/virtualization_tuning_and_optimization_guide/index#sect-Virtualization_Tuning_Optimization_Guide-Networking-Zero_copy_transmit)

```diff
# /etc/modprobe.d/vhost-net.conf
+ options vhost_net	experimental_zcopytx=1
```