Appointments page loading very slowly

I just got appointments+ set up and we are already using it.

However the appointment page is loading incredibly slowly while rest of the site responds normally. This is making the booking process quite confusing since you have to be extra careful that the calendar has refreshed before making an appointment.

Is there a way to diagnose the reason for this? http://tools.pingdom.com/fpt revealed that the 99% of loading time is actually just waiting for the domain, not loading of a specific file etc.

You can try it at http://www.kuntoklinikka.fi/ajanvaraus

Thank you.