This plugin caches the turrets with loaded but the benefit is lower frame times to INCREASE FPS. having the items cached is for performance, If you look at the reviews there is a graph of how this plugin reduces the frame times needed for all turrets.
what is powered switches? Are you using a plugin that is providing power to turrets? This may effect the plugin knowing if it should be on depending on how that plugin implements powerless turrets.
I would be happy to review that plugin if that is the case for you.