take an appointment page take long time to load

Hi
I've realised when i'am using my tablet or my phone ( with wifi conexion) , and i want to visit my site
pruebas.massantia.com/crea-tu-cita
it takes a longer time in refernce with the desktop, but many many more.
Is this a problem that somebody has had before?
I consider that through the tablet or the phone it will take a litle more, but in my case the difference is about 30 seconds.

The loading bar charges till almost the end of it but it remains at the end for about 30-40seconds bofore to reach the end.

Could anybody tell me if it happens before, or make a test on their devices.

Thanks very much