Hi Nikita,
Thanks for reaching out to us. With our plugin, you are loading not only products, but you are also displaying variation attributes. Which will take time to load than without attributes on the archive/shop page.
Could you update your free and premium version of the WooCommerce Variation Swatches plugin?
The current version of swatches plugins is the following.
Variation Swatches for WoooCoommerce – Version 2.0.6
Variation Swatches for WooCommerce Pro – Version 2.0.6
Please make sure you are using the same version.
Thank You
Low speed with plugin turned on
Nikita Samokhvalov