Is there any way to configure nginx to use memcache for storing cache data, as opposed to using files stored on hard drive?
The Nginx HttpMemcachedModule allows the use of Memcached as storage, but does not store HTTP headers with data - all pages served via Memcached storage have the default
The Enhanced Nginx Memached Module is based on the standard module and has additional features which include storing HTTP headers together with data honoring the required HTTP headers.
Probably with HttpMemcachedModule.
Also, consider the StackOverflow thread title "How to configure NGINX with Memcache to serve HTML"
400% improvement? Yes please.