Site loads okay on one server but snail-pace on another.

Hello, I have developed a site for a friend, using my own server as a “test” to show them as the project has progressed. It’s here:

https://thomcurtis.co.uk/greedylittlegirls/

Loads okay, right?

So I was sure we were near completion, and today uploaded it to their server. It’s here:

https://greedylittlegirls.com/

Awful, right? It’s only the home page and the ‘we love’ page that load super slow, and they’re the only two with custom queries in too. But I’ve never had this problem before and it worked fine on my server.

The second server also hosts other sites that use WordPress, and all of them work fine apparently. Although these might be non-customised sites.

I have one plugin enabled which I’ve disabled and nothing changed.
I’ve also tried removing jquery, simpletip.js and easySlider1.7.js, both to no avail.

Really confused, super annoyed!