What should I do about outdated BootCache playlists?
These files are used for boot-time optimisation. The cache is also measured for hit rate, and stores the request pattern into a "history list" for being adaptive in future. If the hit rate is too low, the caching is disabled.

To look under the hood and examine the hit/miss rate

 sudo bootcachecontrol statistics Print


The actual impact of files like app.com.coriolis-systems.iDefrag.playlist should be really minimal.

However, if the application is otherwise completely gone, it is safe to delete all instances of these coriolis-related cache files in /private/var/db/BootCaches/

If these files get recreated it means that there are remnants of the application left, and active.

(Observe this effect by deleting /private/var/db/BootCaches/PreheatedUser/app.com.apple.Safari.playlist It will be created instantly once you relaunch Safari)