Ultra slow loading (more than a minute)

I'm facing an issue on a website I created. The page loading takes a very long time for no reason, and I'm completely lost about the way I could fix it.

Here's a link to the website: Belugas Trio

The weirdest thing is that when I reload the page it loads fast, and i can't determine what is blocking page loading for so long.

Anyone with a hint is welcome!