on Ubuntu 16.04.LTS: MUCH Apt-Cache Cruft, seems to hang?

After installing this long-term build I run UT. about 1,500 items (!) appear in Janitor's "Apt Cache" cruft list, which is kind of amazing. The first 20 or so items clear relatively quick; then things slow wa-a-a-a-y down. Not sure if the process is even running but do not want to interrupt it.