Fix Slow Wordpress Admin Panel (Backend) ASAP

For speed optimization of my website I got help from wp-rocket guys. Their work is not finished yet but speed got better, but because backend is slow and sometimes it gives 522 error cloudflare, they can't continue. Because fixing slow backend is not in the package of advanced configuration of wp rocket cache plugin, so I have to get help from another developer. Problems: 1- The backend is really slow, specially the plugins page. As you can see in the admin top toolbar, query monitor identified some slow queries. I'm not sure if the problem of slow backend is related to those or not. 2- Cloudflare gives error 522 in backend occasionally or Error 403. The problem is in fact related to problem number one, so if we can solve problem number one, I think the number two will be resoved automatically. I am looking for someone who can fix it right away. website: [login to view URL] Thanks