Hello,
I have installed W3 Total cache plugin and your site has very good results https://tools.pingdom.com/#!/elLdBf/https://podaracizasvatba.com/shop/
Load time 1.16 s
PageSpeed Tools gives 90/100 – desktop and 74/100 – mobile. If you optimize images and fix moments with google analytics http://prntscr.com/hfxp6dgoogle you can get better results.
To optimize images you may try tinypng service, it’s better than kraken and has the free plugin for some amount of images.
Size of the images is WP autogenerated size http://prntscr.com/hfxqum for the every product image. I have changed sizes to more correct in your case. Detailed information about these dimensions you can get here https://docs.woocommerce.com/document/fixing-blurry-product-images/
Regards