Yes! I've been waiting for a fast userland OSS network stack forever. There's things like DPDK for IP but nobody has taken up the monumental task of getting TCP working and reliable
Libuinet is the FreeBSD TCP stack in user space (including over netmap) https://github.com/pkelsey/libuinet
There is also work in FD.io on userspace TCP & UDP. https://github.com/FDio/tldk