What that paper really demonstrates is the need for a TLS stack in the kernel that can let userspace daemons benefit from low-level optimizations.
On the other hand, vulnerabilities can become more severe, like this recent one: https://news.ycombinator.com/item?id=9380468
Perhaps full TLS in the kernel isn't necessary, but only the stream encryption - which tends to be the simpler part and thus less likely to have vulnerabilities compared to session negotiation/key exchange/etc.
It might be a rather expensive option, but what do you think of offloading TLS to the NIC? A lot of them do TCP offload already and there are "SSL Accelerator" HSMs available.