I've recently developed a prototype "root zone only" server which can be deployed within local networks to provide an on-site root server without putting a copy of the root zone within each recursor (c.f. RFC 7706). The software is fast, and scalable (it'll run on anything from a RPi3 up to high-end multicore servers, so long as it's running on Linux).
I've also built an (almost) turn-key distribution for the Raspberry Pi, such that a root server can be turned up just by copying the binary image to an SD card, editing a text file to configure its IP address and then powering it on.
This talk will introduce the concept, talk about the Linux networking stack and how packet flows are optimised on multi-core / multi-nic queue systems, and also discuss how the root zone is particularly amenable to pre-computation of answers.