Read these posts about DOM https://docs.wp-rocket.me/article/1412-avoid-an-excessive-dom-size https://isotropic.co/avoid-an-excessive-dom-size-on-your-wordpress-website/
Edit your page and Product elements and enable Lazy loading for the Product elements. It should reduce the DOM structure. Also, you may try to reduce the DOM results on the page by reducing the number of sections of the page/elements in the footer or header.
Check this topic – https://www.8theme.com/topic/high-usage-cpu/