Haven't done any plugins beyond what oh-my-zsh brings with it, but thanks for informing me that I should keep an eye on that .. pretty wild that we have plugins for shells, sheesh. Whats next, an App Store? ;P
oh-my-zsh comes with minimal set of default plugins. The others you can add. Check out oh-my-zsh github page for themes and plugins. I guess the comment in your plugin configuration section will also warn you about adding too many plugins having performance impact.