Divi Site Errors and Optimization

I'm looking for help with a massive Divi site I've built over the last 5 years. I'm looking for it to function properly again and get optimized. I don't need any design edits, new pages or content added, I just need someone to fix the loads of errors and guide me in making it as efficient as possible.

I've even considered scrapping Divi for Gutenburg or another editor since Divi has become so slow. If this is something you specialize in, I need professional guidance. Site is revelryandheart.com