this plugin slows down my site

I disabled this plugin that runs on the home page and my page load speed went from 12 seconds to 3 seconds.

I also noticed that the images are being loaded from https://i0.wp.com/www.gravesite-guardians.com/wp-content/uploads… rather than directly from the site. Why is that?

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