The new project card filtering feature enhances the efficiency of navigating large projects on GitHub by allowing users to quickly locate specific cards through a filter box, regardless of the project's size or the number of contributors. Users can type the card title directly into the filter box for quick access or utilize qualifiers to narrow down cards by aspects such as label or author. These qualifiers offer powerful filtering capabilities, enabling tasks like viewing all cards assigned to a specific user with a simple input. For further details on utilizing GitHub project boards, users are directed to consult the documentation.