opencart site getting random 404\'s, slow page loads.

Our website will sometimes hang up/slow down and take several seconds for a page to load, resulting in random 404's or "MySQL server has gone away". Also, when we are working in the dashboard, processing orders, running scripts that build data feeds, even logging into the dashboard, etc. the frontend is affected and immediately becomes slower/unresponsive until the task is completed in the dashboard. We need a MySQL/Server expert to help us make the pages load immediately when clicked (1 second or less), without errors. And fix the issue of us working in the dashboard, causing the frontend to slow down. We require the programmer to record all changes that are made in a txt located in the root of the site, so we know what you have done. Our server has 24 gigs of ram. We have over 190,000 items. The website is [login to view URL]