Out of curiosity, what are the specs of the server, and how much RAM is "decent"?
It's now setting with 4Gb of RAM, and a load of ~40.
The single biggest issue is that the front-page either shows "marketing" or "your details", so it is dynamic and being generated on-demand.
I'll update to cache.
It'll happen, shortly, but the fastest solution was to re-deploy on a scaling platform.
You might get better response with using perl in fastcgi mode, and using nginx rather than apache.