Did you try putting something like Varnish in front of it? I think you can do the same with nginx, Varnish is just the first thing that popped up in my mind.
At that time, it wasn't a major part of the website -- and I had redis on-hand, so I just did all this work in a couple small python functions inside of our main webapp and used redis to cache. It worked pretty well. I was only introduced to Varnish some years later and I still haven't used it extensively.