Unlike other solutions, the software auto-caches and auto-invalidates SQL; it takes away a developer having to manually configure the cache. Heimdall works with both MySQL and Postgres
I'm working with a company called http://www.heimdalldata.com/ they do SQL auto-caching with no code changes. A perfect replacement for Query Cache if you have a read-heavy application.
They also offer a nice dashboard that helps identify database inefficiencies.
I would try them out to see if you get a performance boost.