I have a list of 60+ modules that I download, via drush, to each new Drupal site that I build. I then enable whatever modules are needed for the specific site I'm working on as I carry out the build.

This means that once the site is launched, there may be modules that are not being called by Drupal core but that are still enabled and/or installed.

Is there an automated way - a specific module, for example - that will tell me which of the modules that are enabled on a site are being called by Drupal core?

Secondly, is there any performance implication for having lots of modules installed on a site if they are not enabled?