Upon returning from vacation I was annoyed by the fact that launching firefox as controls from any of the cds workstation takes forever (more than 5 minutes). I eventually found that the firefox command was overridden by a launcher script (/ligo/home/controls/bin/firefox) that rsyncs user profile to /tmp/somethingsomething, and unfortunately it copies seemingly useless things like Cache.Trash******* that contains over 3.8 million files!

Cache.Trash seems to serve some purpose when firefox exits abnormally and tries to recover session information, but somehow it keeps growing because of firefox bug. I just deleted Cache.Trash.

In addition, though I don't know why you want to rsync your user profile to /tmp, I changed the launcher script so rsync excludes Cache.Trash (or anything starting Cache). I don't care if the previous session is not recovered.