Have you already heard of the new standard for web images from Google? webp is promising to produce much smaller file sizes, which means faster loading times and better SEO scores for you websites.
WordPress 5.8 offers native webp support out of the box when your webserver has the imagemagick plugin installed.
We checked that everything is also working fine with Gutenslider. All you have to do is upload your .webp images in the Media Library or directly in Gutenslider to get you started saving lots of KB. The below image slider uses WordPress and Gutenslider to serve beautiful compressed webp images.