Website very slow to load since theme updated to v5

As per my earlier message today on similar thread, please investigate the very slow loading issues on my client’s site using Enfold.

I have tried many things (deactivated plugins, cache plugins, changing compression settings in Perfomance tab) and have done tests with gtmetrix.com and get very poor results – sometimes even timeout.

Hosting company has advised they have done all they can do, including setting the Memory_Limit to 512M and updated the PHP version to 8.1. They
Client has paid hosting until 2025, so can’t move without losing this investment.

A developer that I paid to check it out says “there is an issue with High Javasrcipt request. These are core files in the WP theme itself (Enfold) that uses javascript.”
He has also said we should change themes, but I really don’t want to do that.

Details for the site are in the private content. Please check and advise what can be done.

Thanks
Nicola