using Impulse the first Image is loading sometimes, sometimes 10 sec.
Used tiny jpg, the image is only 172 kB small, for mobile nearly same.
Problem is, on the frontpage you can not use Image hero (no option for this) what maybe would increase speed, you can only choose slide, and we are using only one slide.
The store is very slow completely not just the slider/hero image. You should take developer assistance to speed up the site.
Anyways, what you can do for the hero image is to completely remove this section and instead use the “Image with text overly” section if you’ve it, and then remove any text and overly from it and you’ll have a fast loading (hopefully) hero banner. Or consider making a hero banner section from scratch if you are willing to code.