My admin bar only shows 6 websites under the "My Sites" section, but the "Multisite Enhancements" plugin retrieves the paths to the favicons of all >100 sites in my network. This results in >100 single DB queries which retrieve the path to a favicon which never appers in my admin bar.

You could probably save a lot of DB queries by replacing wp_get_sites with get_blogs_of_user in Multisite_Add_Admin_Favicon::set_admin_bar_blog_icon().