Hello, LambdaSP,
Thank you for getting in touch with us.
1/ Fixed. Please clear the cache and try to add a product to the cart now.
2/ Please read this article – https://xstore.helpscoutdocs.com/article/100-how-to-speed-up-my-website
If you have any additional questions or concerns, please do not hesitate to reach out to us. Our support team is always available to assist you.
Kind Regards, 8theme team
