This thread claims that additional offload support is planned, but there are no recent progress reports, http://community.ubnt.com/t5/forums/forumtopicprintpage/boar...

Is this a limitation of VyOS or the closed-source offload/acceleration driver?

For Intel hardware, DPDK improves performance even in virtualized environments, http://rishidot.com/blog/cloudcomputing/intel-dpdk-and-cloud... & http://events.linuxfoundation.org/sites/events/files/slides/...