[hinkley]

I don't recall all the details but we did end up with lua to talk to redis or memcached to do some traffic shaping at one point. One for bouncing to error pages before we switched to CDN (long story), and another one for doing something too clever by half about TTFB. It's still really cheap especially on a box that is just doing load balancing and nothing else.

If you wanted to throw another layer of load balancer in, there are consistent hashing-adjacent strategies in nginx+ that would allow you to go from 2 ingress routers to 3 shards with rate limiters to your services, using one KV store per box. But I highly suspect that the latency profile there will look remarkably similar to ingress routers doing rate limiting talking to a KV store cluster.