Example Project: https://github.com/markv12/rails_includes_demo
Going over everything I've learned trying to improve the performance of my Ruby on Rails apps using the includes method. Executing too many SQL queries is the cause of many Rails performance problems. Includes can help, but it can sometimes be hard to tell why includes isn't working. The Rails SQL cache can sometimes hide what's actually going on and Rails features like scopes and the order query method can make includes not work as expected. I use the Rack mini profiler to diagnose unnecessary SQL queries and discuss ways to get rid of them.
