JS_Harris - 10:57 am on Aug 25, 2013 (gmt 0)
Actually Google replaces the cache copy with the requested copy instantly, right in the lightbox, as soon as your browser finishes loading it. It's a slick switcheroo that Google uses because they want instant images and know that their cache will be fast but that our copy will be higher resolution, if not as fast.
Users don't see the actual image unless they click one more time.
I came here looking for a reason as to why my image traffic was off a good 20% since yesterday from Google only. I do use hotlink protection but it blocks 3rd party sites from displaying images inline and Google has been whitelisted for several months.