[Chiuso] The website backend is not loading

Background of the issue:
I have completed and installed the setup on my website, but the website backend is still loading too much. The issue can be seen at: link nascosto

Symptoms:
The website backend is not loading properly and is taking too long to load.

Questions:
Why is the website backend taking too long to load after setup?
How can I resolve the loading issue with the website backend?