Yes it's possible, that's what I did on my site (images, avatars and smileys)
I only proposed the images, but I can create several versions of the mod according to the desires of each one.
There's no need to do it for board icons, it's the caching that does the job. No need for lazy loading.
Of course, one must be interested in the caching of the resources of its forum. This is a very important point!