There are several solutions to this:
1. Lazy Load Images
As none of these images are your content, Lazy Loading them won't matter as Google won't index them for your site anyway. This defers the loading of images until the user scrolls down to see them. How to setup LazyLoad.
The benefit of this is fewer bytes to load on initial page load. Often not all images are necessary to be displayed in the viewport of the user. Once the user starts scrolling we need more and more content that can be loaded in.
2. Set a longer cache policy
This will help with users presented with the same image on multiple pages, so won't affect landing page load times like Lazy Loading. But it will improve overall site speed if these images are used on the same page. One draw back you have here is that if you are pulling these in dynamically and they have the same file name, the cache policy would force the showing of the cached image. This is something you would need to look into, maybe set the cache policy to 1 or days if this is the case.
This can be done in the access file but depends on your server hosting, adding the following code to your htaccess file:
<FilesMatch "\.(?i:gif|jpe?g|png|ico|css|js|swf)$">
<IfModule mod_headers.c>
Header set Cache-Control "max-age=172800, public, must-revalidate"
</IfModule>
</FilesMatch>
3. Reduce the number of images being called by reducing the number of images
This is the least interesting answer for you as you will need to get rid of some of the images.
4. Compress images using htaccess
This will allow you to set cache policies for each file type and ensure that images are compressed:
480 weeks
<FilesMatch "\.(ico|pdf|flv|jpg|jpeg|png|gif|js|css|swf)$">
Header set Cache-Control "max-age=290304000, public"
</FilesMatch>
2 DAYS
<FilesMatch "\.(xml|txt)$">
Header set Cache-Control "max-age=172800, public, must-revalidate"
</FilesMatch>
2 HOURS
<FilesMatch "\.(html|htm)$">
Header set Cache-Control "max-age=7200, must-revalidate"
</FilesMatch>
<ifModule mod_gzip.c>
mod_gzip_on Yes
mod_gzip_dechunk Yes
mod_gzip_item_include file \.(html?|txt|css|js|php|pl)$
mod_gzip_item_include handler ^cgi-script$
mod_gzip_item_include mime ^text/.*
mod_gzip_item_include mime ^application/x-javascript.*
mod_gzip_item_exclude mime ^image/.*
mod_gzip_item_exclude rspheader ^Content-Encoding:.*gzip.*
</ifModule>
The first option is the best and easiest and will reduce load tines significantly. Let me know if this answered your question or if you need some clarification?
