Need a Developer to Evaluate and Adjust an Active WooCommerce Site with Server Issues

I have a very active WooCommerce site that runs great when it runs great, but every once in awhile, everything slows to a crawl. Pages that were fine literally take minutes to load if they load at all. Repeated online tech support chats always end up with me needing the help of a developer. The issues seem to often run along the lines of too many processes running. There are 5 active active site on a VPS server. When our main site goes down, they all go down. I'm fairly technically savvy, but at a certain level, server level issues are beyond my understanding. I need someone to work with me to evaluate our current setup and help me figure out what may need adjusting to prevent the site(s) going down in the future and how to ensure the site loads properly and quickly. If there's an issue in the future, I need someone I can contact who can quickly jump on the issue and help resolve it. Our main concern is this WooCommerce site: jacquespepinart.com. I can supply all the necessary credentials at the appropriate time.