Hello,
In general, our theme is already optimized and don’t have too many resources to make your website slow. Most likely, your website performance suffers from the content you have added to your website. It may happen in case of too many plugins, large not optimized images or other resources. So we suggest you to remove unnecessary plugins, install some kind of JS & CSS optimizing plugins like Better WordPress Minify and a caching plugin like WP Super Cache or use WP Rocket for both tasks. Also, you can use GTmetrix tool to see what makes your website slow and optimize these parts of your website.
The recommended version of the PHP for our theme is 7.0-7.2
Kind Regards
XTemos Studio
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