Learn how to add performance tests that automate benchmark and profile reports. Here I show how to find the bottlenecks to optimize a page. I also show how to compile Ruby with gcdata to get information about memory usage.
A model's ID in the URL is not very helpful to the user. Consider adding the name which can also improve SEO. Learn how to override to_param, add a slug attribute, and make a catch all route for deep nesting.
If your Rails app is content-heavy, consider organizing it in a tree menu structure. Here I show how to add top-level tabs, nested links in a side bar, and breadcrumbs to go up the hierarchy.