My website has a very heavy read traffic. A lot heavier than write traffic.
To improve the performance of my website I have thought of going with master/slave database configuration.
With octopus gem, you don't have to change much of your code to make write queries go to the master db server and read queries go to the slaves.
It's a simple configuration file, as stated here.
I've tried this in the past and It worked quite well. The only problem for me is that when the slave is down, it doesn't "redirect" the queries to the master db server, as I asked here.
But, if you want to configure each individual query destination, it will take some work.
I would suggest you to start mapping your more frequent queries and those that are taking longer to respond. Knowing those queries, you can optimize them individually. This may already solve part of the problem.
If you still need master-slave replication after that, use the octopus gem to change the behaviour only those few complicated queries.