1) Your site is not very fast even with the default theme. Compare:
XStore theme – https://gtmetrix.com/reports/onsofa.online/7WxseHdS/
Storefront theme – https://gtmetrix.com/reports/onsofa.online/iHKGWltc/
2) I see that you use 2 page builders. I would recommend you to recreate WPBakery pages and static blocks using the Elementor page builder and then disable the WPBakery page builder. Using 2 page builders at the same time slows down your site because the page builder uses a lot of resources and calls additional JS, CSS files.
3) I installed the cache plugin and made some changes in Theme Options > Speed optimization. Now speed result of the shop page is the following –