Look into jussi:
https://github.com/steemit/jussi
It's a json-rpc reverse proxy specifically designed to sit in front of steemd and use a redis cache.
It will also route other json-rpc calls that start with other prefixes (e.g. sbds.) to other backend services other than steemd, which comes in handy when you want to run sbds (https://github.com/steemit/sbds) alongside on the same endpoint... like https://api.steemit.com.
Steem on!
Yeah I actually saw a post regarding this. I am going to clone it and check into it today if I get a moment. Might actually save me some time reinventing the wheel