customization – Hello need optimization suggestions

Hello WordPress Community!
Website: https://www.amalfieeceramics.com/
I have WordPress theme : LeArts – Handmade Shop WooCommerce WordPress Theme
https://themeforest.net/item/learts-woocommerce-handmade-shop-wordpress-theme/23379196

Server Configuration: Siteground Cloud Server : 10 RAM, 4 CPU, Unlimited Bandwidth with Cloud Flare On.

Plugin Used for Optimization: WP-Rocket

This website has Speed Optimization Issue and It getting worst after Server Upgrade.
In backend it take too much time to load page and also front end one Ajax is admin-ajax.php?action=learts_get_wishlist_fragments get 4s+ to load

I don’t Know What’s happening even after upgrading server
Please get Some Solution.
Thanks In advance.