There are various services (https://kraken.io/ for example) that offer image optimization. Basically it is drastically reducing the size of the image without reducing the quality by much. In IPS we have GD and Imagemagick settings, but they are not enough apparently, i.e. I have the JPG quality at 70 and when I run the uploaded file through kraken, shortpixel, etc. it is reduced from 400k to 60k without any visual loss of quality.

The more advanced of these services have pretty straight forward API, here is the PHP API for kraken: https://kraken.io/docs/getting-started and even for newbies like me it is not that difficult to have a basic setup. There are few issues however:

- using the API is a bit tricky when you have folders and subfolders, it is designed to handle one file at a time, so some creative programming should be done to rebuild existing attachments. 
- if you create manual script and run it in cron (lets say at midnight each day) it will optimize the files after they are posted, which means that most users will still see the non-optimized file and the advantages of optimization will be reduced.

Thus, I believe a proper app is required, one that can handle the files on the fly. 

I am prepared to pay a fair price for such an app, but I definitely cannot afford to sponsor it on my own, so maybe if enough people express interest some developer will see a market in this. I can imagine people with image heavy communities will like such an app.

I would be interested

Ok, to illustrate what I mean, I will upload one pick here, then run it through the optimization routienes of kraken.io and shortpixel to see the end result...hopefully I selected the right pic for the job  Here it goes. 

Ooops, selected too large image for the free accounts, let me try another one...

 

Shortpixel: pic reduced by 87%

Kraken.io: pic reduced by 60%

 

You can try for yourself with the same pic to see if you notice any differences in quality.

This would be helpful along with Image lazy loading. Which apparently they have "Planned".