Discussion on optimizing and caching onebox images is underway. Lid highlights an issue with large image sizes, citing a 4MB image example from a Wired article. A proposed solution involves serving images via a script that caches and resizes them, similar to Facebook’s approach. sam and solhuebner agree that this issue needs to be fixed, especially considering the impact on mobile bandwidth. However, zogstrip notes that onebox thumbnail optimization has already been implemented.
Continuing the discussion from Image optimisation (work in progress):
The following onebox, The image that is loaded as a thumbnail is 2500x1667 4MB
http://www.wired.com/business/2013/03/five-google-products-at-risk/
Facebook approach isto serve image via a safe_image.php script will cache and resize the original image to a manageable thumbnail size.
onebox should be able to cache / resize external images if needed.
Yes this definitely should be fixed, its not good.
+1 for fixing this as it is consuming a lot of bandwidth on mobile 
I am unsure so I just ask 
is someone working on this or do I just missed another topic on this one?
Closing this since we’ve been optimizing onebox thumbnails for a while now 