Creating a template starting from zero, you certainly bumped into the need to remove unused "css" or "js" that Joomla includes in the front end, the old libraries "mootools", "caption.js" or "html5fallback.js" .

Developing templates, often happen us to have to complete js libraries for a third party. These can have specific prerequisites but not always the ones that Joomla’s core offers are supported. For this reason we have to remove them manually and replace them with others thar are more suitable for the purpose