Fix WooCommerce plugin that is no longer being updated & Fix site performance / lag

Have been using Woocommerce with a combination of plugins and additional functions to get the site working the way we wanted. Has been working great for 3 years, then visualcomposer broke and we had to update our theme 'THE7' to the latest version to get it to work again. Ever since then we have been having issues with load time, timing out, and our quantity on shop page plugin stopped working correctly. I added some customized functions to put a patch on the issue, but the stepping feature is broken and performance is still terrible. If the minimum quantity for ordering a product is 4 then the options should only be 4,8,12, etc when you press up or down on quantity. Now it will go 4,5,6,7,8 and give an error if you don't choose 4 , 8, etc. If we can get the stepping feature working on the category / shop / archive pages then it will be very good for the customer. Also, need to make sure that the page does not reload every time an item is added to the cart. Noticed there are tons of extra entries in the Database from doing restores. Would like help removing all the extra tables as well. Would like help implementing caching functionality. Every time I have tried to do myself, something breaks.