Theme seem to be very slow, and performance is not great

Hi there.

I have some problems with the theme being very slow. I started on your guide: https://xtemos.com/wordpress-performance-optimization-the-ultimate-guide-in-2021/
And according to it, i should see a 0.5s-1.2s score on the test provided. However i am getting past 4s. This is with only WooCommerce, elementor, elementor pro and woodmart core installed as plugins. (Look at image 11)

I also have a issue with thumbnails being loaded WAY too big compared to other themes. all images in image12 is being rendered in the full 1200×1040 size exept for the thumbsnails, they are rendered as 600×600. Thats way more than it has too. If i switch to any other theme, then this issue goes away and the same images are rendered in a way lower size.