LINUX SERVER + WORDPRESS PERFORMANCES OPTIMIZATION

We are currently using Wordpress as a CMS for our website, on its very last update. Our website is very slow, it takes a lot of time to be fully loaded. We are using a server with strong configuration with a full remote access. GTMetrix shows that the website takes 20.8 seconds to be fully loaded, the home page's weight is 1.58 Mo for 71 queries. PageSpeed Insights assigns 65/100 for computer and 58/100 for mobile. We are looking for a Linux specialist, able to optimize our server to its maximum, and who must bring improvements to the following points: - PHP - mySQL - cache - htaccess - all important files for speed optimization - technical features of the server (ram, cpu, ...) - DNS access time - all settings that must improve the loading time of our website (on all kind of devices: phone, tablet, computers, ...) Beyond the server performance aspect, you will be able to detect which queries are slowing down the loading of our Wordpress site and optimize them: - weight of pictures - template's unuseful requests - weight of the template - all possible parameters including the loading time on other devices like tablet or phone. What we will provide: - SSH for remote connexion - phpmyadmin for mysql - imscp if needed - Wordpress credentials - proxmox if needed We need the speedest server as possible to load our pages (especially the Home page) as quickly as possible. Warning: we made custom interactive forms (php/ajax) on our website. Changes must not affect our scripts. It will be necessary to verify this on our forms after every changes. We don't want advises to understand how to resolve these points, we don't have resources to do that. We need a professional able to fix our bugs quickly, respecting the deadlines and the best practices for this task. Automatic or out of field answers will not be selected.