ack will always be slower than ripgrep, but it shouldn't be as slow as it is in burntsushi's tests. In his tests, he's showing run times where ack takes 25x as long to run as ripgrep, and ack shouldn't be NEARLY that slow.
We think that there's something weird about his Perl installation that is making it so slow, but we haven't been able to figure it out.
I will dig back into this and see if I can figure it out. If you look at the recent commit history for ripgrep, you'll see I updated the timings for ack on my benchmark in my README. I have no explanation for it, but ack isn't as slow as it was when I went through this before.
Anyway, my Perl installation is the standard one on Archlinux. I will try on other systems.
We think that there's something weird about his Perl installation that is making it so slow, but we haven't been able to figure it out.
Here's the ticket: https://github.com/beyondgrep/ack3/issues/42
If you have any insight, we'd love to have it. We've been stumped, as you'll see if you read through the issue history.