Segments should have expiry expiration option

[atom-box]

Many segments take 15 to 25 minutes to calculate. This accumulated drag is like barnacles under a ship. We receive emails from users who run a 4 to 6 hour archiving and we tell them "go through the slow segments manually and ask your users if some can be dropped".

The need for many segments is less than permanent.

This new feature would

• add a line in the segment configuration which would allow for an expiry date, set by the user,
• a new config.ini.php option, which would globally make ALL segments have an expiry N months from the day the segment is made
• Custom Alert option: when you click Save and Apply the segment green button, a option is given "[ ] Set an expiration date? Enter your email address and the date here" (The alert uses existing logic, through the existing CustomAlerts.addAlert). The alert is sent when 30 days remain from segment-expiry.

What is the reach? I get ~10 emails a year from folks whose archiving is taking too long. They don't know that they need this feature but they would benefit from it.