Heinrich put the ARTofSHADOWS.com website into a heavy maintenance mode couple days ago warning it may be many days before finished. Somehow it took less than 36 hours, recently flickr did almost the same exact update with a team of engineers and took almost a week. So what happened that nobody can see but the wwebmaster? Apparently content loading issues were found after a mass photo optimization was pushed through. Due to all the sites photos and 10 thumbnails copies per photo it caused a slight loading delay even with tiny files only a nerd would see, this was due to a mass server import in March and April. Any photos in these folders had extra loading time just due to an overload of data and files.
A cleanup, ftp removals, database hacking, then more careful repairing. During this process it was decided that ShortPixel is unreliable, Media Cleaner Pro plugin is absolute trash for the main function is serves. Shortpixel is unreliable on large media sites, the optimizations were ok but the system metadata for the Shortpixel optimizations seemed to forget things often. Media Cleaner Pro just destroys databases by “trying” to delete database entries for media items that don't exist, this was testing 4x and on all 4 it failed and certain plugin functions like the progress bar stopped working.
Good thing AOS had a ton of backups, in the process streamlining the process for large import/exports. The site had quite a few images deleted and they were fixed with new updated galleries as well. A new optimization setting was created for 100k size for 2048 pixel images, before this a 90% quality setting was set and the use of JpegMiniPro. Now the files are just optimized from the source, its much safer this way anyway. Modifications to the sites media center are still being done slowly to remove photos from folders already too big, but with new fresh optimized files.
This was purely a performance and future proofing thing. AOS is run by a webmaster wanting sites to migrate if needed in minutes.