outdated and now incorrect text in README?

Problem/Motivation

    9. Remove any other fields (e.g. Title) from the View, they are not needed
       and will only unnecessarily make the database search more resource heavy
       on the system. i.e. just add the one field to the View, the field nid.

       (Tip: you can create your View however you like, but removing unneeded
       lookups is the most efficient on system resources. You probable also
       don't need the default sort criteria: Content: Post date (desc). Drupal
       normally returns the content in a sensible ID order without processing
       the Post date.

I think this is no longer the case in D8+ views -- the relationship entity is loaded anyway, whatever fields you add -- here we access it without loading anything:

  protected function getResultEntity(ResultRow $row) {
    return $this->options['relationship']
      ? $row->_relationship_entities[$this->options['relationship']]
      : $row->_entity;
  }

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes