Since you are using RapidWeaver 8 and stacks 4, one of the ”5 new features” of stacks 4 was the addition of site images.
The Site Image stack (the new default image stack if you’re using RW8 and stacks 4) uses the revamped RW8 resources. You can see more about this new feature with this video.
This new stack eliminates the “the same image had been uploaded“ multiple times to the web server. It will use the same single image file from resources everywhere on your site it’s used. This also gives the advantage of allowing the browsers to cache the images and only have to download them once and use the same file on every page. This can make subsequent pages render much faster.
As for performance I just recently posted some information on some testing I did on using the resources in RapidWeaver 8 with the new site image stack vs warehoused images.