Old Accounts
Old Accounts
[Caption above the frame:] The internet is filled with derelict accounts aggregating news about friends long forgotten.
[Cueball sits at a desk, typing on a laptop.] Cueball: *Click* Computer (friend): Uhh, is everything OK? Cueball: *Click* Computer (another friend): Dude, what the hell? Cueball: *Click*
[Caption below the frame:] When you find yourself drifting away from a community, remember to clean up after yourself by slowly unfriending everyone, one by one, in the reverse order that you added them.

Cueball is very dramatically following the described process of removing himself from a social network by first unfriending each contact in reverse order that he friended them. Such actions are not necessary on any well-designed website. Actively unfriending people individually could be perceived as rude, antisocial, or in need of help.  On the other hand, if a user simply abandons his or her account without cleaning it up, then even years later, it will still be sitting there, gathering friends' statuses, opinions and comments.
The reverse order to unfriend people refers to practice of correct resource management in computer programming.  Computer programs typically require access to many resources at a time, and some of those resources may only be available insofar as the program has access to other more basic resources.
For example, if you wanted to watch a movie from a rental service, you would first acquire a keep case with a disk inside of it, and then you would remove the DVD from the case in order to play it on a TV.  Once you had watched the movie, you would put the DVD back inside the case.  Then you would return the case to the store.  The process for "releasing" these two resources (the DVD and the keep case) follows the reverse order of how they were obtained: the case was retrieved from the store before the disk was removed, but the disk must be put back before you return the case.
A computer program must release resources in a valid order, though it is often difficult for programmers to ensure this, due to the many paths of execution a program can follow.  If resources are released in the wrong order, then a newer resource may reference an older resource that has already been destroyed, and when attempting to use the remaining resource, a variety of bad things could happen if the program attempted to access the already lost resource.
While resources do not always need to be released in exactly the reverse order of how they were obtained, doing so ensures that, as each resource is released, none of the resources that existed when it was acquired (and thus which it could be dependent upon) will have been released yet.
In the case of unfriending users on a social networking site, it is imagined that Cueball or any other user could have made newer friends through older friends, and as such, that the newer friend should not exist without the older friend and must therefore be released first.
The title text appears to be referencing related issue affecting databases used on websites such as social networking sites. When an account is deactivated, the database entries for users that were friends with the account may maintain a link to it.  This would result in the database storing useless data, so a well-designed database might try to mitigate this.  A well-written program accessing the database would be able to recognize that this data should be ignored.  Since no user account would be directly dependent on the existence of another account, the accounts can safely be deleted without worrying about resource management as described earlier.
Ultimately, the inefficiency of a database containing useless data about deleted accounts is negligible, and in fact it may not even be worthwhile to take the time to update all the entries compared to how little time it would save when performing lookups. "Database linkage accumulation slowdown" really is a thing that Randall just made up. This may be a satire of popular fears of made-up technological problems, often held by those who are not technologically savvy.
[Caption above the frame:] The internet is filled with derelict accounts aggregating news about friends long forgotten.
[Cueball sits at a desk, typing on a laptop.] Cueball: *Click* Computer (friend): Uhh, is everything OK? Cueball: *Click* Computer (another friend): Dude, what the hell? Cueball: *Click*
[Caption below the frame:] When you find yourself drifting away from a community, remember to clean up after yourself by slowly unfriending everyone, one by one, in the reverse order that you added them.
