The next page is the attendee information page, so EE process your selection generates the registrations and sets up the Single Page CheckOut (SPCO for short) to process the registrations. That process does not usually take anywhere near 1 minute, however, it is heavily reliant on your server.
Setting up the above both reads and write to the database so if you’re on a shared host and its under load (from any of the users on that site), it’s going to take longer than when it’s not under load (right now it took 7 seconds for the page to load for me on your site).
So the first question to ask is what type of hosting are you using? Shared?