Having a hard time finding documentation explaining in any depth how date caching works in Drupal 7. Adding a date field to a content type allows a checkbox option that says "Cache dates: Date objects can be created and cached as date fields are loaded, rather than when they are displayed, to improve performance." In what scenarios is it a good idea to select this option? How does it improve performance?
Found this 5 year old comment in the issue thread that gives some more context. Not sure why the enhanced help text didn't make it into the 7.x module, but it helped me make the decision. https://www.drupal.org/project/date/issues/1358790#comment-6327490
In order to display a date, a date object is created. Creating and caching date objects at the time date field data is entered may improve performance. For single-value, non-repeating, date fields caching will be neutral or have a performance benefit. For multiple-value or repeating dates with a large number of values, caching may negatively impact performance as some date objects that are cached may never actually be required.