Hello,

1- Regarding your Button concern, sorry to say but we are unable to check the concerned issue on your Site as the provided WP-ADMIN Login details are not the Super Admin Login details. Kindly, provide Super Admin login details so that we can proceed further with the said issue.

2- Regarding your other concern, please check out the following Theme Article which will help you out in this regard hopefully: https://xtemos.com/wordpress-performance-optimization-the-ultimate-guide-in-2021/

Best Regards