WP FASTEST CACHE PREMIUM BREAKS MY SITE

HI there, I have been trying and trying to get WP Fastest Cache Premium to speed up my site but it makes it SLOWER every time, it breaks my header, it destroys my Woocommerce templates and it stalls horiffically. I have done a lot of testing and it is specific to this plugin, I have been trying for a LONG time to perservere and make it work but it is an absolute nightmare!! Can someone please help me?!?
It is currently deactivated becasue of how embarassingly slow it makes my site.

The page I need help with: [log in to see the link]