I'm using the Field Group module to make accordions on my site, but it loads JQuery and slows the page down. Is there a way to do this without JS?
Yes, you can use the HTML 5 details tag.
On the content type display administration page, create a field group.
For the Format, chose
For Field group label, enter the text you want to show to click to display the rest of the text.
For the Element, enter
For Show Label, select Yes.
For Label element, enter
To style with CSS, add extra CSS classes as needed.