bad performance

I understand your concerns with page load time. Here are some caching recommendations for use with Paid Memberships Pro: https://www.paidmembershipspro.com/documentation/using-caching-plugins-paid-memberships-pro/

Additionally, here is a resource on hosting recommendations. A membership site is a robust platform and has some minimum hosting requirements in order to be a success. See: https://www.paidmembershipspro.com/2013/09/recommendations-web-hosting-support-pmpro/