Thanks! It's weird, but as soon as I tried upgrading to an identical GCP machine running Debian 9 (stretch) and run my database creation process[1], it took many, many times longer to even download the several GB dumps from Wikipedia via wget than it did on Debian 8 (jessie). As the beefy machine I use for the database creation process costs ~40 cents per hour, I figured it wasn't worth it to upgrade to Debian 9 since the Debian 8 machine finished in one hour and worked fine. After trying it a second time a month later and realizing the same thing happened, I added a note for myself in the README about it. I did find some other reports about it online[2] and just decided it wasn't that critical to upgrade it at the moment.

[1] https://github.com/jwngr/sdow#database-creation-process [2] https://lists.debian.org/debian-kernel/2017/12/msg00265.html