I'm going to copy this comment again here just incase you didn't know about unlockables!
We host the image on both IPFS and an image server so the site loads quickly and also for redundancy purposes. We occasionally experience some slowness with the IPFS server and have been looking into that.
As for the second part we have offered unlockables for about 6 months now, this means the artist can upload a lower res image for public viewing and then include whatever they like in the unlockable section that is only accessible to the buyer. Artist aren't forced to use that option but it is there as a choice if they would like to use it :)