I had a landing page with 37 high quality images spread across 5 pages. Used Squash at first to bring down the aggregated size of the images from ~550MB to ~320MB and voila my bounce rates started going down. A few months later i tried out Cloudinary and the conversion rates improved since the biggest bottleneck of the landing page was the images and they were loading smoothly. IMHO one of the low hanging fruits that is worth solving.
I assume by "high quality" your parent comment is referring to photo imagery on a photography oriented site. Even an 18 MP camera (which some phones have nowadays) will generate single images over 100 MB if they are not compressed at all.
Notice that I said "not compressed at all". My Canon T5i is a few hundred dollars, and when I convert the (compressed) raw to an uncompressed TIFF or PNG, it's over 100MB.
It's high by any standards. A 60 MB webpage would take 5 seconds to load on a 100 Mbps home broadband connection, which is well above the median in the United States. On most mobile connections a 60 MB webpage is going to be borderline unusable.
My grandfathered $140/month mobile plan has 14GB of data; 320MB is 70% of a day's bandwidth, or 2% of the month's.
If I wanted to add another GB I could accrue $100 in overages ($0.10/MB), or pay another $25/month. But Bell will charge for another month in advance if you change the current month's plan.
Strangely enough it was only $5/month to up it from 13GB to 14GB :<
All this despite being able to download at 7MB/s; I could blow my cap in half an hour, and another half hour would cost $1,400 if I didn't up the plan.
Edit: I use my cellphone's data heavily, but 20, 40, 50GB cable internet caps are common with a lot of people not understanding what that means for streaming video / downloading pictures.
Adding more info to the post, all of those images were procedurally generated stereo 360 degree photos directly from Unity(Exported at 5K or 4K res). I had built a PoC for a Game Store of sorts that allowed you to view 360 degree images of games(Via Ansel). So the image sizes were humongous and since the landing page served as a usable demo at the time we did not compress the images at first.
