In the home page of my e-shop I usually have banners with links to the (at that time) most important pages.
These banners change frequently, like one to twice a month, and they usually don't have any visible text so I suppose they don't have a big impact on SEO.
They also kind of big, about 1200px wide, and this is a drawback for the mobile version of the site (maybe the desktop one, I'm not sure), so I'd like to use other, smaller images for the mobile view of the site.
So, my thought is to not have a banner at all in the source and just load one later with JS. That way I could load whatever I want depending on the client's device.
So my question is:
How important are those banners for the SEO, considering that they change frequently and they are nothing but images with
Will the speed benefit of loading the content asynchronously be enough to overcome the possible SEO loss?