I know there are several factors in increasing the speed of Joomla sites such as caching, compressing css/js files, module usage, deleting unwanted extensions/templates, photo/video size optimization, deleting unwanted white space in template index.php, etc.
I have been curious about another thing though, for RT templates, do we also need to delete the css style files (or back them up) that aren't being used or does it not matter since the main template css file and parameters will be asking for only 1 css style file and pulling the info from that one.
If anyone has more info about this, I would appreciate that! Hope it's not too dumb of a question.
It's only pulling in the styles and files it needs for your settings in the template.
If you wanted to delete unused files, you could, but sometimes it's nice to have them there when you want to change your site a little bit a while down the road. maybe adding different colors to different pages and stuff.