This is happening with me, too. And my hosting has a lot of resources. It’s definitely not a hosting issue. Also happening with all plugins disabled except HivePress. Tried on different devices and networks.
[EDIT]: I figured it out. It was hanging up due to the mailer not working properly and the fact that the registrations need to be verified via email. I installed WP Mail SMTP and set up Brevo as a third party emailer. Now my emails work, and the registration process took 2 seconds just like it should.