It then installs an updater via cron to check for updated lists every week.

As to your experience with speed, I'm kind of surprised. The only time I noticed a speed difference is when I blackholed domains in the hosts file that didn't resolve to a valid web server (i.e. resolving to 127.0.0.1 without having a web server running), and that's the opposite of what you describe. The pi-hole script also installs lighttpd to serve up a placeholder page, and uses some tricks like mod_expire to improve performance.