Hello,

As we can see, your staging website is much faster now. Here are screenshots from Pagespeed results
https://gyazo.com/6c0708a051897deedb2958b06ffe58b4
https://gyazo.com/a0a652490b7bbd98b50b5b6ab0957303

Note that when the page is not cached (loaded for the first time) it has a very slow response time from the server. So you need to check what is wrong with the server because it loads slowly on the backend too so it is not something caused by the theme.

Kind Regards