It appears the implementation of Happy Eyeballs in 1.22.0 is the origin of
some pretty serious performance regressions that remain even in the latest
Hackney 3.0 branch.
Connection tests:
=== 1.22.0 ===
First call: 9434ms
Second call: 14ms
=== 1.21.0 ===
First call: 228ms
Second call: 16ms
We went back further to 1.20.1 though because of reported problems with the mail
client and ssl_options. That bug was not reproduced by a dev, though, but we'll
trust it for now.
